From: Timofey Titovets <nefelim...@gmail.com> Replace jhash2 with xxhash.
Perf numbers: Intel(R) Xeon(R) CPU E5-2420 v2 @ 2.20GHz ksm: crc32c hash() 12081 MB/s ksm: xxh64 hash() 8770 MB/s ksm: xxh32 hash() 4529 MB/s ksm: jhash2 hash() 1569 MB/s Sioh Lee did some testing: crc32c_intel: 1084.10ns crc32c (no hardware acceleration): 7012.51ns xxhash32: 2227.75ns xxhash64: 1413.16ns jhash2: 5128.30ns As jhash2 always will be slower (for data size like PAGE_SIZE). Don't use it in ksm at all. Use only xxhash for now, because for using crc32c, cryptoapi must be initialized first - that requires some tricky solution to work well in all situations. Link: http://lkml.kernel.org/r/20181023182554.23464-3-nefelim...@gmail.com Signed-off-by: Timofey Titovets <nefelim...@gmail.com> Signed-off-by: leesioh <so...@os.korea.ac.kr> Reviewed-by: Pavel Tatashin <pavel.tatas...@microsoft.com> Reviewed-by: Mike Rapoport <r...@linux.vnet.ibm.com> Reviewed-by: Andrew Morton <a...@linux-foundation.org> Cc: Andrea Arcangeli <aarca...@redhat.com> Signed-off-by: Andrew Morton <a...@linux-foundation.org> Signed-off-by: Kirill Tkhai <ktk...@virtuozzo.com> ===================== Patchset description: ksm: Switch to xxhash hash algorithm xxhash shows better performance in comparison to currently used jhash2: ksm: xxh64 hash() 8770 MB/s ksm: xxh32 hash() 4529 MB/s ksm: jhash2 hash() 1569 MB/s Note, that algorithm module lib/xxhash.c is already in ms kernel [1/3], while [2-3/3] just make ksm to use it (but they also already in akpm tree). This should improve ksm performance in some way. Nick Terrell (1): lib: Add xxhash module Timofey Titovets (2): xxHash: create arch dependent 32/64-bit xxhash() ksm: replace jhash2 with xxhash https://jira.sw.ru/browse/PSBM-90044 (cherry-picked from 5df8dc1eb691271b92562bcfc43b458f3996596a) Signed-off-by: Andrey Zhadchenko <andrey.zhadche...@virtuozzo.com> diff --git a/mm/Kconfig b/mm/Kconfig index 963532b..b64929a 100644 --- a/mm/Kconfig +++ b/mm/Kconfig @@ -292,6 +292,7 @@ config MMU_NOTIFIER config KSM bool "Enable KSM for page merging" depends on MMU + select XXHASH help Enable Kernel Samepage Merging: KSM periodically scans those areas of an application's address space that an app has advised may be diff --git a/mm/ksm.c b/mm/ksm.c index 034e032..5fec98b 100644 --- a/mm/ksm.c +++ b/mm/ksm.c @@ -25,7 +25,7 @@ #include <linux/pagemap.h> #include <linux/rmap.h> #include <linux/spinlock.h> -#include <linux/jhash.h> +#include <linux/xxhash.h> #include <linux/delay.h> #include <linux/kthread.h> #include <linux/wait.h> @@ -1009,7 +1009,7 @@ static u32 calc_checksum(struct page *page) { u32 checksum; void *addr = kmap_atomic(page); - checksum = jhash2(addr, PAGE_SIZE / 4, 17); + checksum = xxhash(addr, PAGE_SIZE, 0); kunmap_atomic(addr); return checksum; } -- 1.8.3.1 _______________________________________________ Devel mailing list Devel@openvz.org https://lists.openvz.org/mailman/listinfo/devel
