From nobody Mon Jun 22 14:09:03 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6C872C433F5 for ; Wed, 23 Mar 2022 03:18:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241466AbiCWDUP (ORCPT ); Tue, 22 Mar 2022 23:20:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42876 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231637AbiCWDUN (ORCPT ); Tue, 22 Mar 2022 23:20:13 -0400 Received: from mail-qv1-xf2c.google.com (mail-qv1-xf2c.google.com [IPv6:2607:f8b0:4864:20::f2c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C6B9F31342 for ; Tue, 22 Mar 2022 20:18:44 -0700 (PDT) Received: by mail-qv1-xf2c.google.com with SMTP id ke15so328824qvb.11 for ; Tue, 22 Mar 2022 20:18:44 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=HuZMniKUiLdmMq0S/smNDGx4nZr+J2VHjPsTBck+11s=; b=Tse20CMLZPb2xi5LDlL7G8zi9e/ZhtX9/urs8GbZmvyP4uSFlC4CZWjoI4aA/TJyvz qghQYdMJQ+pyEUGbMWo9FBTfHMapfLu7tHIX4XirSbAIpnoBipCMJ6EZ03PmxIMGhjW1 okzbtJ8uJ4EO1lPxEQfPOwGJAmG6jP26zu52g0/HxhUJMotkPKJ/sSRDXG721rlw1qzD QEsaNlShMRACfhXdIbQfo4xyjU9cz+lcVORvKr2GnNQ1VmYSylY5FU2JtkhwI2EV7Yqf qAaK9AiJ9R8/45dVaAXa9fu6S8fKx3RMOF7IPXHIED5AFMxcPAxaDrpl4iXWR43LCKrV dnzQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=HuZMniKUiLdmMq0S/smNDGx4nZr+J2VHjPsTBck+11s=; b=BytTRZ71VK0baA2wTDB5Gogu5WLmm97m8b5XbHKzLVhjw7peIqK3VTgZA91lwBvrjw IDxw6qmYgaYd/KJDZvLASTi1Ua5nJJOFy5Av7mMV/VMLW8LrbwjFLDkXm1y6OaB2URoU 1PwIy/MzuIFwoGQkMRUW+GeV1C+o47IZX919JNkKHFXiEMzHZMcLjkeQqnUfmNgnOJH1 cDv3NNG54frK+MwZkw2XopWrygnAqyDA+bVAwvNOi198++dqwgP546eMNfvL7yiGnUCN 1Byl2qmMe8/sIRCUb53J3LmJjQ3L9nGDM2wsZ4j7sGfEvD/W3acSLbhgK/xL0DYWwrCg kKrw== X-Gm-Message-State: AOAM532c2CpZpqmcGIq9ep2U7Jpg+R31IlZU/uEr5CLHQSt83F/t0RU2 Dy/qSVQYl0SE6G9xx8vWUUI= X-Google-Smtp-Source: ABdhPJzhksxHW4/rsLVdg+jn6M3FiJF1MkqN5pSAr6Z+9q+YhbyelyH/4MqEL6Bw9r3GhLufC8dKrg== X-Received: by 2002:ad4:5ccb:0:b0:441:1abe:1b8a with SMTP id iu11-20020ad45ccb000000b004411abe1b8amr11696377qvb.7.1648005523965; Tue, 22 Mar 2022 20:18:43 -0700 (PDT) Received: from localhost.localdomain ([193.203.214.57]) by smtp.gmail.com with ESMTPSA id w13-20020a05622a134d00b002e2280215f6sm2108254qtk.54.2022.03.22.20.18.39 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 22 Mar 2022 20:18:43 -0700 (PDT) From: cgel.zte@gmail.com X-Google-Original-From: yang.yang29@zte.com.cn To: akpm@linux-foundation.org, david@redhat.com Cc: yang.yang29@zte.com.cn, dave.hansen@linux.intel.com, yang.shi@linux.alibaba.com, ran.xiaokai@zte.com.cn, saravanand@fb.com, minchan@kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, xu xin Subject: [PATCH] mm/vmstat: add events for ksm cow Date: Wed, 23 Mar 2022 03:17:31 +0000 Message-Id: <20220323031730.2342930-1-yang.yang29@zte.com.cn> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Yang Yang Users may use ksm by calling madvise(, , MADV_MERGEABLE) when they want to save memory, it's a tradeoff by suffering delay on ksm cow. Users can get to know how much memory ksm saved by reading /sys/kernel/mm/ksm/pages_sharing, but they don't know what's the costs of ksm cow, and this is important of some delay sensitive tasks. So add ksm cow events to help users evaluate whether or how to use ksm. Signed-off-by: Yang Yang Reviewed-by: xu xin Reviewed-by: Ran Xiaokai Reported-by: kernel test robot --- include/linux/vm_event_item.h | 2 ++ mm/memory.c | 18 +++++++++++++++--- mm/vmstat.c | 2 ++ 3 files changed, 19 insertions(+), 3 deletions(-) diff --git a/include/linux/vm_event_item.h b/include/linux/vm_event_item.h index 16a0a4fd000b..6f32be04212f 100644 --- a/include/linux/vm_event_item.h +++ b/include/linux/vm_event_item.h @@ -131,6 +131,8 @@ enum vm_event_item { PGPGIN, PGPGOUT, PSWPIN, PSWPOUT, SWAP_RA_HIT, #ifdef CONFIG_KSM KSM_SWPIN_COPY, + KSM_COW_SUCCESS, + KSM_COW_FAIL, #endif #endif #ifdef CONFIG_X86 diff --git a/mm/memory.c b/mm/memory.c index 4111f97c91a0..06c92f322cdb 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -3257,6 +3257,8 @@ static vm_fault_t do_wp_page(struct vm_fault *vmf) __releases(vmf->ptl) { struct vm_area_struct *vma =3D vmf->vma; + vm_fault_t ret =3D 0; + bool ksm =3D 0; =20 if (userfaultfd_pte_wp(vma, *vmf->pte)) { pte_unmap_unlock(vmf->pte, vmf->ptl); @@ -3294,6 +3296,7 @@ static vm_fault_t do_wp_page(struct vm_fault *vmf) */ if (PageAnon(vmf->page)) { struct page *page =3D vmf->page; + ksm =3D PageKsm(page); =20 /* * We have to verify under page lock: these early checks are @@ -3302,7 +3305,7 @@ static vm_fault_t do_wp_page(struct vm_fault *vmf) * * PageKsm() doesn't necessarily raise the page refcount. */ - if (PageKsm(page) || page_count(page) > 3) + if (ksm || page_count(page) > 3) goto copy; if (!PageLRU(page)) /* @@ -3316,7 +3319,7 @@ static vm_fault_t do_wp_page(struct vm_fault *vmf) goto copy; if (PageSwapCache(page)) try_to_free_swap(page); - if (PageKsm(page) || page_count(page) !=3D 1) { + if (ksm || page_count(page) !=3D 1) { unlock_page(page); goto copy; } @@ -3339,7 +3342,16 @@ static vm_fault_t do_wp_page(struct vm_fault *vmf) get_page(vmf->page); =20 pte_unmap_unlock(vmf->pte, vmf->ptl); - return wp_page_copy(vmf); + ret =3D wp_page_copy(vmf); + + if (ksm) { + if (unlikely(ret & VM_FAULT_ERROR)) + count_vm_event(KSM_COW_FAIL); + else + count_vm_event(KSM_COW_SUCCESS); + } + + return ret; } =20 static void unmap_mapping_range_vma(struct vm_area_struct *vma, diff --git a/mm/vmstat.c b/mm/vmstat.c index d5cc8d739fac..a2c29a5206ec 100644 --- a/mm/vmstat.c +++ b/mm/vmstat.c @@ -1390,6 +1390,8 @@ const char * const vmstat_text[] =3D { "swap_ra_hit", #ifdef CONFIG_KSM "ksm_swpin_copy", + "ksm_cow_success", + "ksm_cow_fail", #endif #endif #ifdef CONFIG_X86 --=20 2.25.1