From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lf0-f70.google.com (mail-lf0-f70.google.com [209.85.215.70]) by kanga.kvack.org (Postfix) with ESMTP id 23ADF6B0007 for ; Wed, 18 Apr 2018 15:32:36 -0400 (EDT) Received: by mail-lf0-f70.google.com with SMTP id j69-v6so852117lfg.6 for ; Wed, 18 Apr 2018 12:32:36 -0700 (PDT) Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id l188-v6sor539191lfe.15.2018.04.18.12.32.33 for (Google Transport Security); Wed, 18 Apr 2018 12:32:33 -0700 (PDT) From: Timofey Titovets Subject: [PATCH V6 0/2 RESEND] KSM replace hash algo with faster hash Date: Wed, 18 Apr 2018 22:32:18 +0300 Message-Id: <20180418193220.4603-1-timofey.titovets@synesis.ru> Sender: owner-linux-mm@kvack.org List-ID: To: linux-mm@kvack.org Cc: Timofey Titovets , Andrea Arcangeli , kvm@vger.kernel.org, leesioh From: Timofey Titovets Currently used jhash are slow enough and replace it allow as to make KSM less cpu hungry. About speed (in kernel): ksm: crc32c hash() 12081 MB/s ksm: xxh64 hash() 8770 MB/s ksm: xxh32 hash() 4529 MB/s ksm: jhash2 hash() 1569 MB/s By sioh Lee tests (copy from other mail): Test platform: openstack cloud platform (NEWTON version) Experiment node: openstack based cloud compute node (CPU: xeon E5-2620 v3, memory 64gb) VM: (2 VCPU, RAM 4GB, DISK 20GB) * 4 Linux kernel: 4.14 (latest version) KSM setup - sleep_millisecs: 200ms, pages_to_scan: 200 Experiment process Firstly, we turn off KSM and launch 4 VMs. Then we turn on the KSM and measure the checksum computation time until full_scans become two. The experimental results (the experimental value is the average of the measured values) crc32c_intel: 1084.10ns crc32c (no hardware acceleration): 7012.51ns xxhash32: 2227.75ns xxhash64: 1413.16ns jhash2: 5128.30ns In summary, the result shows that crc32c_intel has advantages over all of the hash function used in the experiment. (decreased by 84.54% compared to crc32c, 78.86% compared to jhash2, 51.33% xxhash32, 23.28% compared to xxhash64) the results are similar to those of Timofey. So: - Fisrt patch implement compile time pickup of fastest implementation of xxhash for target platform. - Second implement logic in ksm, what test speed of hashes and pickup fastest hash Thanks. CC: Andrea Arcangeli CC: linux-mm@kvack.org CC: kvm@vger.kernel.org CC: leesioh Timofey Titovets (2): xxHash: create arch dependent 32/64-bit xxhash() ksm: replace jhash2 with faster hash include/linux/xxhash.h | 23 +++++++++++++ mm/Kconfig | 2 ++ mm/ksm.c | 93 +++++++++++++++++++++++++++++++++++++++++++++++--- 3 files changed, 114 insertions(+), 4 deletions(-) -- 2.14.1