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authorBarry Song <v-songbaohua@oppo.com>2022-07-20 12:37:37 +0300
committerWill Deacon <will@kernel.org>2022-07-20 12:52:40 +0300
commitd0637c505f8a1d8c4088642f1f3e9e3b22da14f6 (patch)
tree21477ebad7dceb27f5d1797bbd11fb077d1d6974 /mm
parenta111daf0c53ae91e71fd2bfe7497862d14132e3e (diff)
downloadlinux-d0637c505f8a1d8c4088642f1f3e9e3b22da14f6.tar.xz
arm64: enable THP_SWAP for arm64
THP_SWAP has been proven to improve the swap throughput significantly on x86_64 according to commit bd4c82c22c367e ("mm, THP, swap: delay splitting THP after swapped out"). As long as arm64 uses 4K page size, it is quite similar with x86_64 by having 2MB PMD THP. THP_SWAP is architecture-independent, thus, enabling it on arm64 will benefit arm64 as well. A corner case is that MTE has an assumption that only base pages can be swapped. We won't enable THP_SWAP for ARM64 hardware with MTE support until MTE is reworked to coexist with THP_SWAP. A micro-benchmark is written to measure thp swapout throughput as below, unsigned long long tv_to_ms(struct timeval tv) { return tv.tv_sec * 1000 + tv.tv_usec / 1000; } main() { struct timeval tv_b, tv_e;; #define SIZE 400*1024*1024 volatile void *p = mmap(NULL, SIZE, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); if (!p) { perror("fail to get memory"); exit(-1); } madvise(p, SIZE, MADV_HUGEPAGE); memset(p, 0x11, SIZE); /* write to get mem */ gettimeofday(&tv_b, NULL); madvise(p, SIZE, MADV_PAGEOUT); gettimeofday(&tv_e, NULL); printf("swp out bandwidth: %ld bytes/ms\n", SIZE/(tv_to_ms(tv_e) - tv_to_ms(tv_b))); } Testing is done on rk3568 64bit Quad Core Cortex-A55 platform - ROCK 3A. thp swp throughput w/o patch: 2734bytes/ms (mean of 10 tests) thp swp throughput w/ patch: 3331bytes/ms (mean of 10 tests) Cc: "Huang, Ying" <ying.huang@intel.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Hugh Dickins <hughd@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Steven Price <steven.price@arm.com> Cc: Yang Shi <shy828301@gmail.com> Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com> Signed-off-by: Barry Song <v-songbaohua@oppo.com> Link: https://lore.kernel.org/r/20220720093737.133375-1-21cnbao@gmail.com Signed-off-by: Will Deacon <will@kernel.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/swap_slots.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/mm/swap_slots.c b/mm/swap_slots.c
index 2a65a89b5b4d..10b94d64cc25 100644
--- a/mm/swap_slots.c
+++ b/mm/swap_slots.c
@@ -307,7 +307,7 @@ swp_entry_t folio_alloc_swap(struct folio *folio)
entry.val = 0;
if (folio_test_large(folio)) {
- if (IS_ENABLED(CONFIG_THP_SWAP))
+ if (IS_ENABLED(CONFIG_THP_SWAP) && arch_thp_swp_supported())
get_swap_pages(1, &entry, folio_nr_pages(folio));
goto out;
}