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2024-01-11riscv: Add support for BATCHED_UNMAP_TLB_FLUSHAlexandre Ghiti1-1/+1
Allow to defer the flushing of the TLB when unmapping pages, which allows to reduce the numbers of IPI and the number of sfence.vma. The ubenchmarch used in commit 43b3dfdd0455 ("arm64: support batched/deferred tlb shootdown during page reclamation/migration") that was multithreaded to force the usage of IPI shows good performance improvement on all platforms: * Unmatched: ~34% * TH1520 : ~78% * Qemu : ~81% In addition, perf on qemu reports an important decrease in time spent dealing with IPIs: Before: 68.17% main [kernel.kallsyms] [k] __sbi_rfence_v02_call After : 8.64% main [kernel.kallsyms] [k] __sbi_rfence_v02_call * Benchmark: int stick_this_thread_to_core(int core_id) { int num_cores = sysconf(_SC_NPROCESSORS_ONLN); if (core_id < 0 || core_id >= num_cores) return EINVAL; cpu_set_t cpuset; CPU_ZERO(&cpuset); CPU_SET(core_id, &cpuset); pthread_t current_thread = pthread_self(); return pthread_setaffinity_np(current_thread, sizeof(cpu_set_t), &cpuset); } static void *fn_thread (void *p_data) { int ret; pthread_t thread; stick_this_thread_to_core((int)p_data); while (1) { sleep(1); } return NULL; } int main() { volatile unsigned char *p = mmap(NULL, SIZE, PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANONYMOUS, -1, 0); pthread_t threads[4]; int ret; for (int i = 0; i < 4; ++i) { ret = pthread_create(&threads[i], NULL, fn_thread, (void *)i); if (ret) { printf("%s", strerror (ret)); } } memset(p, 0x88, SIZE); for (int k = 0; k < 10000; k++) { /* swap in */ for (int i = 0; i < SIZE; i += 4096) { (void)p[i]; } /* swap out */ madvise(p, SIZE, MADV_PAGEOUT); } for (int i = 0; i < 4; i++) { pthread_cancel(threads[i]); } for (int i = 0; i < 4; i++) { pthread_join(threads[i], NULL); } return 0; } Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com> Reviewed-by: Jisheng Zhang <jszhang@kernel.org> Tested-by: Jisheng Zhang <jszhang@kernel.org> # Tested on TH1520 Tested-by: Nam Cao <namcao@linutronix.de> Link: https://lore.kernel.org/r/20240108193640.344929-1-alexghiti@rivosinc.com Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2023-09-11Documentation: Drop IA64 from feature descriptionsArd Biesheuvel7-7/+0
Itanium (IA64) is going away, so drop it from the kernel feature documentation. Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2023-08-31Merge tag 'docs-6.6' of git://git.lwn.net/linuxLinus Torvalds1-2/+3
Pull documentation updates from Jonathan Corbet: "Documentation work keeps chugging along; this includes: - Work from Carlos Bilbao to integrate rustdoc output into the generated HTML documentation. This took some work to figure out how to do it without slowing the docs build and without creating people who don't have Rust installed, but Carlos got there - Move the loongarch and mips architecture documentation under Documentation/arch/ - Some more maintainer documentation from Jakub ... plus the usual assortment of updates, translations, and fixes" * tag 'docs-6.6' of git://git.lwn.net/linux: (56 commits) Docu: genericirq.rst: fix irq-example input: docs: pxrc: remove reference to phoenix-sim Documentation: serial-console: Fix literal block marker docs/mm: remove references to hmm_mirror ops and clean typos docs/zh_CN: correct regi_chg(),regi_add() to region_chg(),region_add() Documentation: Fix typos Documentation/ABI: Fix typos scripts: kernel-doc: fix macro handling in enums scripts: kernel-doc: parse DEFINE_DMA_UNMAP_[ADDR|LEN] Documentation: riscv: Update boot image header since EFI stub is supported Documentation: riscv: Add early boot document Documentation: arm: Add bootargs to the table of added DT parameters docs: kernel-parameters: Refer to the correct bitmap function doc: update params of memhp_default_state= docs: Add book to process/kernel-docs.rst docs: sparse: fix invalid link addresses docs: vfs: clean up after the iterate() removal docs: Add a section on surveys to the researcher guidelines docs: move mips under arch docs: move loongarch under arch ...
2023-08-18arm64: support batched/deferred tlb shootdown during page reclamation/migrationBarry Song1-1/+1
On x86, batched and deferred tlb shootdown has lead to 90% performance increase on tlb shootdown. on arm64, HW can do tlb shootdown without software IPI. But sync tlbi is still quite expensive. Even running a simplest program which requires swapout can prove this is true, #include <sys/types.h> #include <unistd.h> #include <sys/mman.h> #include <string.h> int main() { #define SIZE (1 * 1024 * 1024) volatile unsigned char *p = mmap(NULL, SIZE, PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANONYMOUS, -1, 0); memset(p, 0x88, SIZE); for (int k = 0; k < 10000; k++) { /* swap in */ for (int i = 0; i < SIZE; i += 4096) { (void)p[i]; } /* swap out */ madvise(p, SIZE, MADV_PAGEOUT); } } Perf result on snapdragon 888 with 8 cores by using zRAM as the swap block device. ~ # perf record taskset -c 4 ./a.out [ perf record: Woken up 10 times to write data ] [ perf record: Captured and wrote 2.297 MB perf.data (60084 samples) ] ~ # perf report # To display the perf.data header info, please use --header/--header-only options. # To display the perf.data header info, please use --header/--header-only options. # # # Total Lost Samples: 0 # # Samples: 60K of event 'cycles' # Event count (approx.): 35706225414 # # Overhead Command Shared Object Symbol # ........ ....... ................. ...... # 21.07% a.out [kernel.kallsyms] [k] _raw_spin_unlock_irq 8.23% a.out [kernel.kallsyms] [k] _raw_spin_unlock_irqrestore 6.67% a.out [kernel.kallsyms] [k] filemap_map_pages 6.16% a.out [kernel.kallsyms] [k] __zram_bvec_write 5.36% a.out [kernel.kallsyms] [k] ptep_clear_flush 3.71% a.out [kernel.kallsyms] [k] _raw_spin_lock 3.49% a.out [kernel.kallsyms] [k] memset64 1.63% a.out [kernel.kallsyms] [k] clear_page 1.42% a.out [kernel.kallsyms] [k] _raw_spin_unlock 1.26% a.out [kernel.kallsyms] [k] mod_zone_state.llvm.8525150236079521930 1.23% a.out [kernel.kallsyms] [k] xas_load 1.15% a.out [kernel.kallsyms] [k] zram_slot_lock ptep_clear_flush() takes 5.36% CPU in the micro-benchmark swapping in/out a page mapped by only one process. If the page is mapped by multiple processes, typically, like more than 100 on a phone, the overhead would be much higher as we have to run tlb flush 100 times for one single page. Plus, tlb flush overhead will increase with the number of CPU cores due to the bad scalability of tlb shootdown in HW, so those ARM64 servers should expect much higher overhead. Further perf annonate shows 95% cpu time of ptep_clear_flush is actually used by the final dsb() to wait for the completion of tlb flush. This provides us a very good chance to leverage the existing batched tlb in kernel. The minimum modification is that we only send async tlbi in the first stage and we send dsb while we have to sync in the second stage. With the above simplest micro benchmark, collapsed time to finish the program decreases around 5%. Typical collapsed time w/o patch: ~ # time taskset -c 4 ./a.out 0.21user 14.34system 0:14.69elapsed w/ patch: ~ # time taskset -c 4 ./a.out 0.22user 13.45system 0:13.80elapsed Also tested with benchmark in the commit on Kunpeng920 arm64 server and observed an improvement around 12.5% with command `time ./swap_bench`. w/o w/ real 0m13.460s 0m11.771s user 0m0.248s 0m0.279s sys 0m12.039s 0m11.458s Originally it's noticed a 16.99% overhead of ptep_clear_flush() which has been eliminated by this patch: [root@localhost yang]# perf record -- ./swap_bench && perf report [...] 16.99% swap_bench [kernel.kallsyms] [k] ptep_clear_flush It is tested on 4,8,128 CPU platforms and shows to be beneficial on large systems but may not have improvement on small systems like on a 4 CPU platform. Also this patch improve the performance of page migration. Using pmbench and tries to migrate the pages of pmbench between node 0 and node 1 for 100 times for 1G memory, this patch decrease the time used around 20% (prev 18.338318910 sec after 13.981866350 sec) and saved the time used by ptep_clear_flush(). Link: https://lkml.kernel.org/r/20230717131004.12662-5-yangyicong@huawei.com Tested-by: Yicong Yang <yangyicong@hisilicon.com> Tested-by: Xin Hao <xhao@linux.alibaba.com> Tested-by: Punit Agrawal <punit.agrawal@bytedance.com> Signed-off-by: Barry Song <v-songbaohua@oppo.com> Signed-off-by: Yicong Yang <yangyicong@hisilicon.com> Reviewed-by: Kefeng Wang <wangkefeng.wang@huawei.com> Reviewed-by: Xin Hao <xhao@linux.alibaba.com> Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Nadav Amit <namit@vmware.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Barry Song <baohua@kernel.org> Cc: Darren Hart <darren@os.amperecomputing.com> Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com> Cc: lipeifeng <lipeifeng@oppo.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ryan Roberts <ryan.roberts@arm.com> Cc: Steven Miao <realmz6@gmail.com> Cc: Will Deacon <will@kernel.org> Cc: Zeng Tao <prime.zeng@hisilicon.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-07-14Documentation/features: Refresh support files for 6.5Tiezhu Yang1-2/+2
Run the refresh script [1] to document the recent feature additions. [1] Documentation/features/scripts/features-refresh.sh Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn> Signed-off-by: Jonathan Corbet <corbet@lwn.net> Link: https://lore.kernel.org/r/1689060720-4628-3-git-send-email-yangtiezhu@loongson.cn
2023-07-14Documentation/features: Check ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUTTiezhu Yang1-0/+1
ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT selects ARCH_HAS_ELF_RANDOMIZE, so add ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT as another Kconfig check for ELF-ASLR feature, then the refresh script can be used to handle this case for all archs. Co-developed-by: Xi Ruoyao <xry111@xry111.site> Signed-off-by: Xi Ruoyao <xry111@xry111.site> Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn> Signed-off-by: Jonathan Corbet <corbet@lwn.net> Link: https://lore.kernel.org/r/1689060720-4628-2-git-send-email-yangtiezhu@loongson.cn
2022-12-15Merge tag 'riscv-for-linus-6.2-mw1' of ↵Linus Torvalds1-1/+1
git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux Pull RISC-V updates from Palmer Dabbelt: - Support for the T-Head PMU via the perf subsystem - ftrace support for rv32 - Support for non-volatile memory devices - Various fixes and cleanups * tag 'riscv-for-linus-6.2-mw1' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux: (52 commits) Documentation: RISC-V: patch-acceptance: s/implementor/implementer Documentation: RISC-V: Mention the UEFI Standards Documentation: RISC-V: Allow patches for non-standard behavior Documentation: RISC-V: Fix a typo in patch-acceptance riscv: Fixup compile error with !MMU riscv: Fix P4D_SHIFT definition for 3-level page table mode riscv: Apply a static assert to riscv_isa_ext_id RISC-V: Add some comments about the shadow and overflow stacks RISC-V: Align the shadow stack RISC-V: Ensure Zicbom has a valid block size RISC-V: Introduce riscv_isa_extension_check RISC-V: Improve use of isa2hwcap[] riscv: Don't duplicate _ALTERNATIVE_CFG* macros riscv: alternatives: Drop the underscores from the assembly macro names riscv: alternatives: Don't name unused macro parameters riscv: Don't duplicate __ALTERNATIVE_CFG in __ALTERNATIVE_CFG_2 riscv: mm: call best_map_size many times during linear-mapping riscv: Move cast inside kernel_mapping_[pv]a_to_[vp]a riscv: Fix crash during early errata patching riscv: boot: add zstd support ...
2022-12-05Documentation/features: Use loongarch instead of loongTiezhu Yang7-7/+7
The official arch name is LoongArch [1], we should use small letter loongarch instead of loong in Documentation/features, just use the features-refresh.sh to refresh all the related files. [1] https://www.kernel.org/doc/html/latest/loongarch/index.html Fixes: 5860800e8696 ("Documentation/features: Update the arch support status files") Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn> Link: https://lore.kernel.org/r/1670156327-9631-3-git-send-email-yangtiezhu@loongson.cn Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2022-10-29riscv: Enable HAVE_ARCH_HUGE_VMAP for 64BITLiu Shixin1-1/+1
This sets the HAVE_ARCH_HUGE_VMAP option, and defines the required page table functions. With this feature, ioremap area will be mapped with huge page granularity according to its actual size. This feature can be disabled by kernel parameter "nohugeiomap". Signed-off-by: Liu Shixin <liushixin2@huawei.com> Reviewed-by: Björn Töpel <bjorn@kernel.org> Tested-by: Björn Töpel <bjorn@kernel.org> Link: https://lore.kernel.org/r/20221012120038.1034354-2-liushixin2@huawei.com [Palmer: minor formatting] Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2022-06-27arm64: Add HAVE_IOREMAP_PROT supportKefeng Wang1-1/+1
With ioremap_prot() definition from generic ioremap, also move pte_pgprot() from hugetlbpage.c into pgtable.h, then arm64 could have HAVE_IOREMAP_PROT, which will enable generic_access_phys() code, it is useful for debug, eg, gdb. Acked-by: Catalin Marinas <catalin.marinas@arm.com> Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com> Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com> Link: https://lore.kernel.org/r/20220607125027.44946-7-wangkefeng.wang@huawei.com Signed-off-by: Will Deacon <will@kernel.org>
2022-06-09Documentation/features: Update the arch support status filesZheng Zengkai7-1/+8
The arch support status files don't match reality as of v5.19-rc1, use the features-refresh.sh to refresh all the arch-support.txt files in place. The main effect is to add entries for the new loong architecture. Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com> Link: https://lore.kernel.org/r/20220609025656.143460-1-zhengzengkai@huawei.com Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2022-04-04Merge branch 'remove-h8300' of git://git.infradead.org/users/hch/misc into ↵Arnd Bergmann7-7/+0
asm-generic * 'remove-h8300' of git://git.infradead.org/users/hch/misc: remove the h8300 architecture This is clearly the least actively maintained architecture we have at the moment, and probably the least useful. It is now the only one that does not support MMUs at all, and most of the boards only support 4MB of RAM, out of which the defconfig kernel needs more than half just for .text/.data. Guenter Roeck did the original patch to remove the architecture in 2013 after it had already been obsolete for a while, and Yoshinori Sato brought it back in a much more modern form in 2015. Looking at the git history since the reinstantiation, it's clear that almost all commits in the tree are build fixes or cross-architecture cleanups: $ git log --no-merges --format=%an v4.5.. arch/h8300/ | sort | uniq -c | sort -rn | head -n 12 25 Masahiro Yamada 18 Christoph Hellwig 14 Mike Rapoport 9 Arnd Bergmann 8 Mark Rutland 7 Peter Zijlstra 6 Kees Cook 6 Ingo Molnar 6 Al Viro 5 Randy Dunlap 4 Yury Norov Signed-off-by: Arnd Bergmann <arnd@arndb.de>
2022-03-07nds32: Remove the architectureAlan Kao7-7/+0
The nds32 architecture, also known as AndeStar V3, is a custom 32-bit RISC target designed by Andes Technologies. Support was added to the kernel in 2016 as the replacement RISC-V based V5 processors were already announced, and maintained by (current or former) Andes employees. As explained by Alan Kao, new customers are now all using RISC-V, and all known nds32 users are already on longterm stable kernels provided by Andes, with no development work going into mainline support any more. While the port is still in a reasonably good shape, it only gets worse over time without active maintainers, so it seems best to remove it before it becomes unusable. As always, if it turns out that there are mainline users after all, and they volunteer to maintain the port in the future, the removal can be reverted. Link: https://lore.kernel.org/linux-mm/YhdWNLUhk+x9RAzU@yamatobi.andestech.com/ Link: https://lore.kernel.org/lkml/20220302065213.82702-1-alankao@andestech.com/ Link: https://www.andestech.com/en/products-solutions/andestar-architecture/ Signed-off-by: Alan Kao <alankao@andestech.com> [arnd: rewrite changelog to provide more background] Signed-off-by: Arnd Bergmann <arnd@arndb.de>
2022-02-23remove the h8300 architectureChristoph Hellwig7-7/+0
Signed-off-by: Christoph Hellwig <hch@lst.de>
2021-09-12Merge tag 'riscv-for-linus-5.15-mw1' of ↵Linus Torvalds1-1/+1
git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux Pull more RISC-V updates from Palmer Dabbelt: - A pair of defconfig additions, for NVMe and the EFI filesystem localization options. - A larger address space for stack randomization. - A cleanup to our install rules. - A DTS update for the Microchip Icicle board, to fix the serial console. - Support for build-time table sorting, which allows us to have __ex_table read-only. * tag 'riscv-for-linus-5.15-mw1' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux: riscv: Move EXCEPTION_TABLE to RO_DATA segment riscv: Enable BUILDTIME_TABLE_SORT riscv: dts: microchip: mpfs-icicle: Fix serial console riscv: move the (z)install rules to arch/riscv/Makefile riscv: Improve stack randomisation on RV64 riscv: defconfig: enable NLS_CODEPAGE_437, NLS_ISO8859_1 riscv: defconfig: enable BLK_DEV_NVME
2021-09-11riscv: Improve stack randomisation on RV64Kefeng Wang1-1/+1
This enlarges the bits availiable for stack randomisation on RV64 from the default of 8MiB to 1GiB, to match arm64 and x86. Also, update the documentation to reflect our support for stack randomisation. Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com> [Palmer: commit text] Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
2021-08-24Documentation/features/vm: correct huge-vmap APIsMark Rutland1-1/+1
In commit: bbc180a5adb05ee8 ("mm: HUGE_VMAP arch support cleanup") We replaced: * ioremap_pud_enabled() with arch_vmap_pud_supported() * ioremap_pmd_enabled() with arch_vmap_pmd_supported() Update the documentation accordingly. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: linux-doc@vger.kernel.org Link: https://lore.kernel.org/r/20210817091621.16799-1-mark.rutland@arm.com Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2021-08-12Documentation/features/vm: riscv supports THP nowJisheng Zhang1-1/+1
After commit e88b333142e4 ("riscv: mm: add THP support on 64-bit"), riscv can support THP. Signed-off-by: Jisheng Zhang <jszhang@kernel.org> Link: https://lore.kernel.org/r/20210805002739.23f44d2d@xhacker Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2021-03-15Documentation/features: mark BATCHED_UNMAP_TLB_FLUSH doesn't apply to ARM64Barry Song1-1/+1
BATCHED_UNMAP_TLB_FLUSH is used on x86 to do batched tlb shootdown by sending one IPI to TLB flush all entries after unmapping pages rather than sending an IPI to flush each individual entry. On arm64, tlb shootdown is done by hardware. Flush instructions are innershareable. The local flushes are limited to the boot (1 per CPU) and when a task is getting a new ASID. So marking this feature as "TODO" is not proper. ".." isn't good as well. So this patch adds a "N/A" for this kind of features which are not needed on some architectures. Signed-off-by: Barry Song <song.bao.hua@hisilicon.com> Acked-by: Will Deacon <will@kernel.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Andy Lutomirski <luto@kernel.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will@kernel.org> Link: https://lore.kernel.org/r/20210223003230.11976-1-song.bao.hua@hisilicon.com Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2021-02-25Documentation: features: remove c6x referencesArnd Bergmann7-7/+0
The references to arch/c6x are obsolete now that the architecture is gone. Remove them. Signed-off-by: Arnd Bergmann <arnd@arndb.de> Link: https://lore.kernel.org/r/20210225142841.3385428-1-arnd@kernel.org Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-09-14s390/pci: Implement ioremap_wc/prot() with MIONiklas Schnelle1-1/+1
With our current support for the new MIO PCI instructions, write combining/write back MMIO memory can be obtained via the pci_iomap_wc() and pci_iomap_wc_range() functions. This is achieved by using the write back address for a specific bar as provided in clp_store_query_pci_fn() These functions are however not widely used and instead drivers often rely on ioremap_wc() and ioremap_prot(), which on other platforms enable write combining using a PTE flag set through the pgrprot value. While we do not have a write combining flag in the low order flag bits of the PTE like x86_64 does, with MIO support, there is a write back bit in the physical address (bit 1 on z15) and thus also the PTE. Which bit is used to toggle write back and whether it is available at all, is however not fixed in the architecture. Instead we get this information from the CLP Store Logical Processor Characteristics for PCI command. When the write back bit is not provided we fall back to the existing behavior. Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com> Reviewed-by: Pierre Morel <pmorel@linux.ibm.com> Reviewed-by: Gerald Schaefer <gerald.schaefer@linux.ibm.com> Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
2020-07-01arch: remove unicore32 portMike Rapoport7-7/+0
The unicore32 port do not seem maintained for a long time now, there is no upstream toolchain that can create unicore32 binaries and all the links to prebuilt toolchains for unicore32 are dead. Even compilers that were available are not supported by the kernel anymore. Guenter Roeck says: I have stopped building unicore32 images since v4.19 since there is no available compiler that is still supported by the kernel. I am surprised that support for it has not been removed from the kernel. Remove unicore32 port. Signed-off-by: Mike Rapoport <rppt@linux.ibm.com> Acked-by: Arnd Bergmann <arnd@arndb.de> Acked-by: Guenter Roeck <linux@roeck-us.net>
2020-06-04mm: remove CONFIG_HAVE_MEMBLOCK_NODE_MAP optionMike Rapoport1-34/+0
CONFIG_HAVE_MEMBLOCK_NODE_MAP is used to differentiate initialization of nodes and zones structures between the systems that have region to node mapping in memblock and those that don't. Currently all the NUMA architectures enable this option and for the non-NUMA systems we can presume that all the memory belongs to node 0 and therefore the compile time configuration option is not required. The remaining few architectures that use DISCONTIGMEM without NUMA are easily updated to use memblock_add_node() instead of memblock_add() and thus have proper correspondence of memblock regions to NUMA nodes. Still, free_area_init_node() must have a backward compatible version because its semantics with and without CONFIG_HAVE_MEMBLOCK_NODE_MAP is different. Once all the architectures will use the new semantics, the entire compatibility layer can be dropped. To avoid addition of extra run time memory to store node id for architectures that keep memblock but have only a single node, the node id field of the memblock_region is guarded by CONFIG_NEED_MULTIPLE_NODES and the corresponding accessors presume that in those cases it is always 0. Signed-off-by: Mike Rapoport <rppt@linux.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Hoan Tran <hoan@os.amperecomputing.com> [arm64] Acked-by: Catalin Marinas <catalin.marinas@arm.com> [arm64] Cc: Baoquan He <bhe@redhat.com> Cc: Brian Cain <bcain@codeaurora.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Greentime Hu <green.hu@gmail.com> Cc: Greg Ungerer <gerg@linux-m68k.org> Cc: Guan Xuetao <gxt@pku.edu.cn> Cc: Guo Ren <guoren@kernel.org> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Helge Deller <deller@gmx.de> Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Ley Foon Tan <ley.foon.tan@intel.com> Cc: Mark Salter <msalter@redhat.com> Cc: Matt Turner <mattst88@gmail.com> Cc: Max Filippov <jcmvbkbc@gmail.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Michal Hocko <mhocko@kernel.org> Cc: Michal Simek <monstr@monstr.eu> Cc: Nick Hu <nickhu@andestech.com> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Richard Weinberger <richard@nod.at> Cc: Rich Felker <dalias@libc.org> Cc: Russell King <linux@armlinux.org.uk> Cc: Stafford Horne <shorne@gmail.com> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de> Cc: Tony Luck <tony.luck@intel.com> Cc: Vineet Gupta <vgupta@synopsys.com> Cc: Yoshinori Sato <ysato@users.sourceforge.jp> Link: http://lkml.kernel.org/r/20200412194859.12663-4-rppt@kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-05-25Documentation/features: Refresh the arch support status filesBjörn Töpel2-2/+2
I was manually editing the arch-support.txt for eBPF-JIT, when I realized the refresh script [1] has not been run for a while. Let's fix that, so that the entries are more up-to-date. [1] Documentation/features/scripts/features-refresh.sh Signed-off-by: Björn Töpel <bjorn.topel@gmail.com> Link: https://lore.kernel.org/r/20200523191135.21889-1-bjorn.topel@gmail.com Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-02-19documentation: vm: Advertise support for pte_special in riscvAlexandre Ghiti1-1/+1
Risc-V architecture has actually supported pte_special since its merge upstream, simply add this info to the documentation. Signed-off-by: Alexandre Ghiti <alex@ghiti.fr> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2019-01-07Documentation/features: Add csky kernel featuresGuo Ren8-0/+8
core/ cBPF-JIT : TODO | core/ eBPF-JIT : TODO | core/ generic-idle-thread : ok | core/ jump-labels : TODO | core/ tracehook : ok | debug/ KASAN : TODO | debug/ gcov-profile-all : TODO | debug/ kgdb : TODO | debug/ kprobes-on-ftrace : TODO | debug/ kprobes : TODO | debug/ kretprobes : TODO | debug/ optprobes : TODO | debug/ stackprotector : TODO | debug/ uprobes : TODO | debug/ user-ret-profiler : TODO | io/ dma-contiguous : ok | locking/ cmpxchg-local : TODO | locking/ lockdep : TODO | locking/ queued-rwlocks : ok | locking/ queued-spinlocks : TODO | locking/ rwsem-optimized : TODO | perf/ kprobes-event : TODO | perf/ perf-regs : TODO | perf/ perf-stackdump : TODO | sched/ membarrier-sync-core : TODO | sched/ numa-balancing : .. | seccomp/ seccomp-filter : TODO | time/ arch-tick-broadcast : TODO | time/ clockevents : ok | time/ context-tracking : TODO | time/ irq-time-acct : TODO | time/ modern-timekeeping : ok | time/ virt-cpuacct : TODO | vm/ ELF-ASLR : TODO | vm/ PG_uncached : TODO | vm/ THP : .. | vm/ batch-unmap-tlb-flush: TODO | vm/ huge-vmap : TODO | vm/ ioremap_prot : TODO | vm/ numa-memblock : .. | vm/ pte_special : TODO | Signed-off-by: Guo Ren <ren_guo@c-sky.com> Cc: Arnd Bergmann <arnd@arndb.de>
2018-11-05MIPS: Enable IOREMAP_PROT config option for MIPS cpusHassan Naveed1-1/+1
Allows the users of ptrace to access memory mapped by the ptraced process using the same cache coherency attributes as the original process. For example while using gdb with ioremap_prot() incorporated, both gdb and the process being traced will have same cache coherency attributes. Signed-off-by: Hassan Naveed <hnaveed@wavecomp.com> Signed-off-by: Paul Burton <paul.burton@mips.com> Patchwork: https://patchwork.linux-mips.org/patch/20955/ Cc: <linux-mips@linux-mips.org>
2018-06-08mm: introduce ARCH_HAS_PTE_SPECIALLaurent Dufour1-1/+1
Currently the PTE special supports is turned on in per architecture header files. Most of the time, it is defined in arch/*/include/asm/pgtable.h depending or not on some other per architecture static definition. This patch introduce a new configuration variable to manage this directly in the Kconfig files. It would later replace __HAVE_ARCH_PTE_SPECIAL. Here notes for some architecture where the definition of __HAVE_ARCH_PTE_SPECIAL is not obvious: arm __HAVE_ARCH_PTE_SPECIAL which is currently defined in arch/arm/include/asm/pgtable-3level.h which is included by arch/arm/include/asm/pgtable.h when CONFIG_ARM_LPAE is set. So select ARCH_HAS_PTE_SPECIAL if ARM_LPAE. powerpc __HAVE_ARCH_PTE_SPECIAL is defined in 2 files: - arch/powerpc/include/asm/book3s/64/pgtable.h - arch/powerpc/include/asm/pte-common.h The first one is included if (PPC_BOOK3S & PPC64) while the second is included in all the other cases. So select ARCH_HAS_PTE_SPECIAL all the time. sparc: __HAVE_ARCH_PTE_SPECIAL is defined if defined(__sparc__) && defined(__arch64__) which are defined through the compiler in sparc/Makefile if !SPARC32 which I assume to be if SPARC64. So select ARCH_HAS_PTE_SPECIAL if SPARC64 There is no functional change introduced by this patch. Link: http://lkml.kernel.org/r/1523433816-14460-2-git-send-email-ldufour@linux.vnet.ibm.com Signed-off-by: Laurent Dufour <ldufour@linux.vnet.ibm.com> Suggested-by: Jerome Glisse <jglisse@redhat.com> Reviewed-by: Jerome Glisse <jglisse@redhat.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.vnet.ibm.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will.deacon@arm.com> Cc: Yoshinori Sato <ysato@users.sourceforge.jp> Cc: Rich Felker <dalias@libc.org> Cc: David S. Miller <davem@davemloft.net> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Vineet Gupta <vgupta@synopsys.com> Cc: Palmer Dabbelt <palmer@sifive.com> Cc: Albert Ou <albert@sifive.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: David Rientjes <rientjes@google.com> Cc: Robin Murphy <robin.murphy@arm.com> Cc: Christophe LEROY <christophe.leroy@c-s.fr> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-05-11Revert "Documentation/features/vm: Remove arch support status file for ↵Jonathan Corbet1-0/+33
'pte_special'" The removal of this file appears to have been premature; it's not a feature enabled by Kconfig, but it's a arch-level feature regardless. Put it back for now until some happy future time when we decide how we really want to document such features. This reverts commit 2bef69a385b4c1c01d8abae0aa035f0ffa051f07. Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2018-05-08Documentation/features/vm: Remove arch support status file for 'pte_special'Andrea Parri1-33/+0
Suggested-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Andrea Parri <andrea.parri@amarulasolutions.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2018-05-08Documentation/features: Refresh the arch support status files in placeAndrea Parri8-2/+18
Now that the script 'features-refresh.sh' is available, uses this script to refresh all the arch-support.txt files in place. Signed-off-by: Andrea Parri <andrea.parri@amarulasolutions.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2018-03-26Documentation: arch-support: remove obsolete architecturesArnd Bergmann8-48/+0
A number of architecture ports are obsolete and getting dropped, so we no longer want to track the respective features. We already removed the lines for metag and mn10300, this does the same edits for all the others. For the remaining 21 architectures, this shows how many are known to implement each given feature: 19 time/modern-timekeeping/arch-support.txt 19 time/clockevents/arch-support.txt 15 core/tracehook/arch-support.txt 14 core/generic-idle-thread/arch-support.txt 13 locking/lockdep/arch-support.txt 12 io/dma-api-debug/arch-support.txt 11 debug/kgdb/arch-support.txt 10 time/virt-cpuacct/arch-support.txt 9 debug/kretprobes/arch-support.txt 9 debug/kprobes/arch-support.txt 8 vm/THP/arch-support.txt 8 vm/pte_special/arch-support.txt 8 vm/numa-memblock/arch-support.txt 8 io/sg-chain/arch-support.txt 7 perf/kprobes-event/arch-support.txt 7 locking/rwsem-optimized/arch-support.txt 7 debug/gcov-profile-all/arch-support.txt 7 core/jump-labels/arch-support.txt 7 core/BPF-JIT/arch-support.txt 6 vm/ELF-ASLR/arch-support.txt 6 time/context-tracking/arch-support.txt 6 seccomp/seccomp-filter/arch-support.txt 6 debug/stackprotector/arch-support.txt 5 time/irq-time-acct/arch-support.txt 5 io/dma-contiguous/arch-support.txt 5 debug/uprobes/arch-support.txt 4 vm/ioremap_prot/arch-support.txt 4 time/arch-tick-broadcast/arch-support.txt 4 perf/perf-stackdump/arch-support.txt 4 perf/perf-regs/arch-support.txt 3 debug/KASAN/arch-support.txt 2 vm/PG_uncached/arch-support.txt 2 vm/huge-vmap/arch-support.txt 2 sched/numa-balancing/arch-support.txt 2 sched/membarrier-sync-core/arch-support.txt 2 locking/cmpxchg-local/arch-support.txt 2 debug/optprobes/arch-support.txt 2 debug/kprobes-on-ftrace/arch-support.txt 1 vm/TLB/arch-support.txt 1 locking/queued-spinlocks/arch-support.txt 1 locking/queued-rwlocks/arch-support.txt 1 debug/user-ret-profiler/arch-support.txt 0 lib/strncasecmp/arch-support.txt Note that the list does not include riscv or nds32 yet, these still need to be added. Signed-off-by: Arnd Bergmann <arnd@arndb.de>
2018-03-10mn10300: Remove the architectureDavid Howells8-8/+0
Remove the MN10300 arch as the hardware is defunct. Suggested-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: David Howells <dhowells@redhat.com> cc: Masahiro Yamada <yamada.masahiro@socionext.com> cc: linux-am33-list@redhat.com Signed-off-by: Arnd Bergmann <arnd@arndb.de>
2018-02-22docs: Remove remaining references to metagJames Hogan8-8/+0
Remove any remaining references to the Meta architecture in Documentation/, primarily from Documentation/features/. Signed-off-by: James Hogan <jhogan@kernel.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: linux-metag@vger.kernel.org Cc: linux-doc@vger.kernel.org
2017-05-01docs: remove all references to AVR32 architectureHans-Christian Noren Egtvedt8-8/+0
The AVR32 architecture support has been removed from the Linux kernel, hence remove all references to it from Documentation. Signed-off-by: Hans-Christian Noren Egtvedt <egtvedt@samfundet.no> Signed-off-by: Håvard Skinnemoen <hskinnemoen@gmail.com> Signed-off-by: Nicolas Ferre <nicolas.ferre@microchip.com> Acked-by: Andy Shevchenko <andy.shevchenko@gmail.com> Acked-by: Boris Brezillon <boris.brezillon@free-electrons.com>
2016-02-18arm64: add support for ioremap() block mappingsArd Biesheuvel1-1/+1
This wires up the existing generic huge-vmap feature, which allows ioremap() to use PMD or PUD sized block mappings. It also adds support to the unmap path for dealing with block mappings, which will allow us to unmap the __init region using unmap_kernel_range() in a subsequent patch. Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2016-01-16mm, thp: remove infrastructure for handling splitting PMDsKirill A. Shutemov1-40/+0
With new refcounting we don't need to mark PMDs splitting. Let's drop code to handle this. Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Tested-by: Sasha Levin <sasha.levin@oracle.com> Tested-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Jerome Marchand <jmarchan@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Rik van Riel <riel@redhat.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Steve Capper <steve.capper@linaro.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-10-17Documentation/features/vm: THP now supported by ARCVineet Gupta1-1/+1
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
2015-10-09Documentation/features/vm: pte_special now supported by ARCVineet Gupta1-1/+1
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
2015-09-09Merge tag 'metag-for-v4.3' of ↵Linus Torvalds1-1/+1
git://git.kernel.org/pub/scm/linux/kernel/git/jhogan/metag Pull metag updates from James Hogan: "Metag architecture changes for v4.3. Just a couple of changes for v4.3-rc1. A preparatory IRQ patch to prepare for moving irq_data struct members, and a tweak to Documentation/features since Meta2 could support THP" * tag 'metag-for-v4.3' of git://git.kernel.org/pub/scm/linux/kernel/git/jhogan/metag: Documentation/features/vm: Meta2 is capable of THP metag/irq: Use access helper irq_data_get_affinity_mask()
2015-09-07Documentation/features/vm: Meta2 is capable of THPJames Hogan1-1/+1
Change metag Transparent Huge Pages (THP) support from .. to TODO. Meta2 has variable sized pages, between 4KB and 4MB, specified at the 1st level page table level, and already supports hugetlbfs, so supporting THP is theoretically possible too. Signed-off-by: James Hogan <james.hogan@imgtec.com> Acked-by: Ingo Molnar <mingo@kernel.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: linux-metag@vger.kernel.org Cc: linux-doc@vger.kernel.org
2015-09-05Documentation/features/vm: add feature description and arch support status ↵Mel Gorman1-0/+40
for batched TLB flush after unmap Signed-off-by: Mel Gorman <mgorman@suse.de> Acked-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-06-03Documentation/features/vm: Add feature description and arch support status ↵Ingo Molnar1-0/+40
file for 'ELF-ASLR' Cc: <linux-api@vger.kernel.org> Cc: <linux-arch@vger.kernel.org> Cc: <linux-kernel@vger.kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Josh Triplett <josh@joshtriplett.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-06-03Documentation/features/vm: Add feature description and arch support status ↵Ingo Molnar1-0/+40
file for 'ioremap_prot' Cc: <linux-api@vger.kernel.org> Cc: <linux-arch@vger.kernel.org> Cc: <linux-kernel@vger.kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Josh Triplett <josh@joshtriplett.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-06-03Documentation/features/vm: Add feature description and arch support status ↵Ingo Molnar1-0/+40
file for 'THP' Cc: <linux-api@vger.kernel.org> Cc: <linux-arch@vger.kernel.org> Cc: <linux-kernel@vger.kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Josh Triplett <josh@joshtriplett.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-06-03Documentation/features/vm: Add feature description and arch support status ↵Ingo Molnar1-0/+40
file for 'pmdp_splitting_flush' Cc: <linux-api@vger.kernel.org> Cc: <linux-arch@vger.kernel.org> Cc: <linux-kernel@vger.kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Josh Triplett <josh@joshtriplett.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-06-03Documentation/features/vm: Add feature description and arch support status ↵Ingo Molnar1-0/+40
file for 'pte_special' Cc: <linux-api@vger.kernel.org> Cc: <linux-arch@vger.kernel.org> Cc: <linux-kernel@vger.kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Josh Triplett <josh@joshtriplett.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-06-03Documentation/features/vm: Add feature description and arch support status ↵Ingo Molnar1-0/+40
file for 'huge-vmap' Cc: <linux-api@vger.kernel.org> Cc: <linux-arch@vger.kernel.org> Cc: <linux-kernel@vger.kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Josh Triplett <josh@joshtriplett.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-06-03Documentation/features/vm: Add feature description and arch support status ↵Ingo Molnar1-0/+40
file for 'PG_uncached' Cc: <linux-api@vger.kernel.org> Cc: <linux-arch@vger.kernel.org> Cc: <linux-kernel@vger.kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Josh Triplett <josh@joshtriplett.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-06-03Documentation/features/vm: Add feature description and arch support status ↵Ingo Molnar1-0/+40
file for 'numa-memblock' Cc: <linux-api@vger.kernel.org> Cc: <linux-arch@vger.kernel.org> Cc: <linux-kernel@vger.kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Josh Triplett <josh@joshtriplett.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org>