From mboxrd@z Thu Jan 1 00:00:00 1970 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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3B294C433EF for ; Tue, 5 Apr 2022 21:22:21 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id A15A96B0072; Tue, 5 Apr 2022 17:22:10 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 9C4C36B0073; Tue, 5 Apr 2022 17:22:10 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 88D7E6B0074; Tue, 5 Apr 2022 17:22:10 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0067.hostedemail.com [216.40.44.67]) by kanga.kvack.org (Postfix) with ESMTP id 7B6076B0072 for ; Tue, 5 Apr 2022 17:22:10 -0400 (EDT) Received: from smtpin24.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 2E8B0183C16B6 for ; Tue, 5 Apr 2022 21:22:00 +0000 (UTC) X-FDA: 79324098000.24.1DBFB05 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf27.hostedemail.com (Postfix) with ESMTP id 9B6F340041 for ; Tue, 5 Apr 2022 21:21:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=Vfnds4uZwOUw8zPinp55S3drsKWUUrjkD5pxZmDfQ3o=; b=UE9salMD8CEHOMHRKgSqk1ysa4 +Zb8ubeM4QI2ErLIm70Y4BRN2nXRdyL+r/3EWfgaNkAjGzYvbec7vhKYE2uod+I9xbucnfeb4m0HU lRTNfmvRPN5IzMdnPags8ZPe7zz/KKEQ+N6TLon1FgZEO2tYuIWqSDIC5BYVl90nu3zUQpvI+dMFS HGCtYR/g0Y1c+8XmM8EkbAinT1rcrVVrPO2x2jy7n07PnzjcJ/cinP7k0C8R9w6f7Nczk1v9TsVcL KEy3AsIypYKS8H0evy+GXwixPEX+lSfwm/hlmJlrY4fj6qjfgGeiqSVjg3zxtDgtvKZwsaSFrTk6l +V2RFV7A==; Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1nbqcb-0074AY-PZ; Tue, 05 Apr 2022 21:21:53 +0000 Date: Tue, 5 Apr 2022 22:21:53 +0100 From: Matthew Wilcox To: Yang Shi Cc: Roman Gushchin , Dave Chinner , Hillf Danton , MM , Mel Gorman , Stephen Brennan , Yu Zhao , David Hildenbrand , LKML Subject: Re: [RFC] mm/vmscan: add periodic slab shrinker Message-ID: References: <20220402072103.5140-1-hdanton@sina.com> <20220403005618.5263-1-hdanton@sina.com> <20220404010948.GV1609613@dread.disaster.area> <20220405051710.GW1609613@dread.disaster.area> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 9B6F340041 X-Stat-Signature: e5m4eh5jkgss7unoitsrdynrfsi51if1 X-Rspam-User: Authentication-Results: imf27.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=UE9salMD; dmarc=none; spf=none (imf27.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org X-HE-Tag: 1649193719-933061 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue, Apr 05, 2022 at 01:58:59PM -0700, Yang Shi wrote: > Yeah, I agree it actually doesn't make too much sense to return the > number of reclaimed objects. Other part of vmscan returns the number > of base pages, the sizes of slab objects are varied, it may be much > smaller than a page, for example, dentry may be 192 bytes. >From the point of view of vmscan, it only cares about the number of pages freed because it's trying to free pages. But from the point of view of trying to keep the number of non-useful objects in check, the number of objects freed is more important, and it doesn't matter whether we ended up freeing any pages because we made memory available for this slab cache.