From nobody Sat Feb 7 18:25:37 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 A6368C77B61 for ; Thu, 13 Apr 2023 08:34:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229795AbjDMIe6 (ORCPT ); Thu, 13 Apr 2023 04:34:58 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36468 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229575AbjDMIe4 (ORCPT ); Thu, 13 Apr 2023 04:34:56 -0400 Received: from mxct.zte.com.cn (mxct.zte.com.cn [183.62.165.209]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 34ABF2108 for ; Thu, 13 Apr 2023 01:34:55 -0700 (PDT) Received: from mse-fl1.zte.com.cn (unknown [10.5.228.132]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mxct.zte.com.cn (FangMail) with ESMTPS id 4PxtDY0lZhz50FXF; Thu, 13 Apr 2023 16:34:53 +0800 (CST) Received: from szxlzmapp07.zte.com.cn ([10.5.230.251]) by mse-fl1.zte.com.cn with SMTP id 33D8Ykbp007431; Thu, 13 Apr 2023 16:34:46 +0800 (+08) (envelope-from yang.yang29@zte.com.cn) Received: from mapi (szxlzmapp01[null]) by mapi (Zmail) with MAPI id mid14; Thu, 13 Apr 2023 16:34:49 +0800 (CST) Date: Thu, 13 Apr 2023 16:34:49 +0800 (CST) X-Zmail-TransId: 2b036437bea9356-74909 X-Mailer: Zmail v1.0 Message-ID: <202304131634494948454@zte.com.cn> Mime-Version: 1.0 From: To: , Cc: , , Subject: =?UTF-8?B?W1BBVENIIGxpbnV4LW5leHQgdjJdIG1tOiB3b3JraW5nc2V0OiB1cGRhdGUgZGVzY3JpcHRpb24gb2YgdGhlIHNvdXJjZSBmaWxl?= X-MAIL: mse-fl1.zte.com.cn 33D8Ykbp007431 X-Fangmail-Gw-Spam-Type: 0 X-Fangmail-Anti-Spam-Filtered: true X-Fangmail-MID-QID: 6437BEAD.000/4PxtDY0lZhz50FXF Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Yang Yang The calculation of workingset size is the core logic of handling refault, it had been updated several times[1][2] after workingset.c was created[3]. But the description hadn't been updated accordingly, this mismatch may confuse the readers. So we update the description to make it consistent to the code.=20 [1] commit 34e58cac6d8f ("mm: workingset: let cache workingset challenge an= on") [2] commit aae466b0052e ("mm/swap: implement workingset detection for anony= mous LRU") [3] commit a528910e12ec ("mm: thrash detection-based file cache sizing") Signed-off-by: Yang Yang --- change for v2 - Update commit of workingset_refault() suggested Johannes We= iner. See https://lore.kernel.org/all/20230316143007.GC116016@cmpxchg.org/ --- mm/workingset.c | 23 +++++++++++++++++------ 1 file changed, 17 insertions(+), 6 deletions(-) diff --git a/mm/workingset.c b/mm/workingset.c index a304e8571d54..b864eec49ddd 100644 --- a/mm/workingset.c +++ b/mm/workingset.c @@ -111,9 +111,20 @@ * * NR_inactive + (R - E) <=3D NR_inactive + NR_active * - * which can be further simplified to + * If we have swap we should consider about NR_inactive_anon and + * NR_active_anon, so for page cache and anonymous respectively: * - * (R - E) <=3D NR_active + * NR_inactive_file + (R - E) <=3D NR_inactive_file + NR_active_file + * + NR_inactive_anon + NR_active_anon + * + * NR_inactive_anon + (R - E) <=3D NR_inactive_anon + NR_active_anon + * + NR_inactive_file + NR_active_file + * + * Which can be further simplified to: + * + * (R - E) <=3D NR_active_file + NR_inactive_anon + NR_active_anon + * + * (R - E) <=3D NR_active_anon + NR_inactive_file + NR_active_file * * Put into words, the refault distance (out-of-cache) can be seen as * a deficit in inactive list space (in-cache). If the inactive list @@ -130,14 +141,14 @@ * are no longer in active use. * * So when a refault distance of (R - E) is observed and there are at - * least (R - E) active pages, the refaulting page is activated - * optimistically in the hope that (R - E) active pages are actually + * least (R - E) pages in the userspace workingset, the refaulting page + * is activated optimistically in the hope that (R - E) pages are actually * used less frequently than the refaulting page - or even not used at * all anymore. * * That means if inactive cache is refaulting with a suitable refault * distance, we assume the cache workingset is transitioning and put - * pressure on the current active list. + * pressure on the current workingset. * * If this is wrong and demotion kicks in, the pages which are truly * used more frequently will be reactivated while the less frequently @@ -468,7 +479,7 @@ void workingset_refault(struct folio *folio, void *shad= ow) * don't activate pages that couldn't stay resident even if * all the memory was available to the workingset. For page * cache whether workingset competition needs to consider - * anon or not depends on having swap. + * anon or not depends on having free swap sapce. */ workingset_size =3D lruvec_page_state(eviction_lruvec, NR_ACTIVE_FILE); /* For anonymous page */ --=20 2.25.1