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authorLinus Torvalds <torvalds@linux-foundation.org>2022-03-23 02:11:53 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2022-03-23 02:11:53 +0300
commit3bf03b9a0839c9fb06927ae53ebd0f960b19d408 (patch)
tree06114247eb7760edca7b57cc0108a351ffe1971b /Documentation/dev-tools
parent3fe2f7446f1e029b220f7f650df6d138f91651f2 (diff)
parent15423a52cc84e23bc11e4a903cd775adc7c6ab00 (diff)
downloadlinux-3bf03b9a0839c9fb06927ae53ebd0f960b19d408.tar.xz
Merge branch 'akpm' (patches from Andrew)
Merge updates from Andrew Morton: - A few misc subsystems: kthread, scripts, ntfs, ocfs2, block, and vfs - Most the MM patches which precede the patches in Willy's tree: kasan, pagecache, gup, swap, shmem, memcg, selftests, pagemap, mremap, sparsemem, vmalloc, pagealloc, memory-failure, mlock, hugetlb, userfaultfd, vmscan, compaction, mempolicy, oom-kill, migration, thp, cma, autonuma, psi, ksm, page-poison, madvise, memory-hotplug, rmap, zswap, uaccess, ioremap, highmem, cleanups, kfence, hmm, and damon. * emailed patches from Andrew Morton <akpm@linux-foundation.org>: (227 commits) mm/damon/sysfs: remove repeat container_of() in damon_sysfs_kdamond_release() Docs/ABI/testing: add DAMON sysfs interface ABI document Docs/admin-guide/mm/damon/usage: document DAMON sysfs interface selftests/damon: add a test for DAMON sysfs interface mm/damon/sysfs: support DAMOS stats mm/damon/sysfs: support DAMOS watermarks mm/damon/sysfs: support schemes prioritization mm/damon/sysfs: support DAMOS quotas mm/damon/sysfs: support DAMON-based Operation Schemes mm/damon/sysfs: support the physical address space monitoring mm/damon/sysfs: link DAMON for virtual address spaces monitoring mm/damon: implement a minimal stub for sysfs-based DAMON interface mm/damon/core: add number of each enum type values mm/damon/core: allow non-exclusive DAMON start/stop Docs/damon: update outdated term 'regions update interval' Docs/vm/damon/design: update DAMON-Idle Page Tracking interference handling Docs/vm/damon: call low level monitoring primitives the operations mm/damon: remove unnecessary CONFIG_DAMON option mm/damon/paddr,vaddr: remove damon_{p,v}a_{target_valid,set_operations}() mm/damon/dbgfs-test: fix is_target_id() change ...
Diffstat (limited to 'Documentation/dev-tools')
-rw-r--r--Documentation/dev-tools/kfence.rst12
1 files changed, 12 insertions, 0 deletions
diff --git a/Documentation/dev-tools/kfence.rst b/Documentation/dev-tools/kfence.rst
index ac6b89d1a8c3..936f6aaa75c8 100644
--- a/Documentation/dev-tools/kfence.rst
+++ b/Documentation/dev-tools/kfence.rst
@@ -41,6 +41,18 @@ guarded by KFENCE. The default is configurable via the Kconfig option
``CONFIG_KFENCE_SAMPLE_INTERVAL``. Setting ``kfence.sample_interval=0``
disables KFENCE.
+The sample interval controls a timer that sets up KFENCE allocations. By
+default, to keep the real sample interval predictable, the normal timer also
+causes CPU wake-ups when the system is completely idle. This may be undesirable
+on power-constrained systems. The boot parameter ``kfence.deferrable=1``
+instead switches to a "deferrable" timer which does not force CPU wake-ups on
+idle systems, at the risk of unpredictable sample intervals. The default is
+configurable via the Kconfig option ``CONFIG_KFENCE_DEFERRABLE``.
+
+.. warning::
+ The KUnit test suite is very likely to fail when using a deferrable timer
+ since it currently causes very unpredictable sample intervals.
+
The KFENCE memory pool is of fixed size, and if the pool is exhausted, no
further KFENCE allocations occur. With ``CONFIG_KFENCE_NUM_OBJECTS`` (default
255), the number of available guarded objects can be controlled. Each object