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 X-Spam-Level: X-Spam-Status: No, score=-1.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B19BCC06510 for ; Tue, 2 Jul 2019 20:03:22 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 6AA1E21852 for ; Tue, 2 Jul 2019 20:03:22 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="Tiln9LxM" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6AA1E21852 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id D632A6B0003; Tue, 2 Jul 2019 16:03:21 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id D12C98E0003; Tue, 2 Jul 2019 16:03:21 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id C00D28E0001; Tue, 2 Jul 2019 16:03:21 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from mail-pg1-f199.google.com (mail-pg1-f199.google.com [209.85.215.199]) by kanga.kvack.org (Postfix) with ESMTP id 8907F6B0003 for ; Tue, 2 Jul 2019 16:03:21 -0400 (EDT) Received: by mail-pg1-f199.google.com with SMTP id a21so51984pgh.11 for ; Tue, 02 Jul 2019 13:03:21 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:dkim-signature:date:from:to:cc:subject :message-id:in-reply-to:references:mime-version :content-transfer-encoding; bh=Kcly/tuUbH1oIMLuOpvBwc3nXKhDlCKcUqNazXXJwlI=; b=ujJFF4B+OovGGAlq7T2QyjxeFIFApf8k/q4bzu5y0FOVgynhcD+RF+5pdpDEFl1qo1 YJg6UlQfEVJuBh7UHVbnwODKE/zjJaibl+16MQ44ZD+RdYDUnmgHjwN0dIqe/Q5cAHRV 2g4vTz4wEiee7yvoUlDk7SRFdQMLPMKcryqWN87JB301tCWctU7E0gVRpUPt3fPqUWbV +ywHCV/YZhX5sam6CZkUZPWPDgnyTHa4p5vLPM8UHiZoe0ivHHeY/zK7JyGAkmeNrzHO YDzj2n8TRPnCVL/xmFr3GJSQG2S8FzL6X/Dv0GF+dq4FBvQ7A2h6CeG9zjpGctGFdb4i jKAg== X-Gm-Message-State: APjAAAVlluul3611cc39zQRf8JgIsl2L9n5IQX+v0IrReY5Sq8TOWp7k uylqDbTy0AGWTJRwEcLIwBzSuzBiGZ5A8hDmpnI48EPcj8ab9lx3QvDI8WzvRHjipC9Zv0l+B40 SEcIWPANWejuxZW8YaNa4nUGVVdUpsu57BCjQsTqLmzU5xj5hYBt1V5WxOsy5gMwfpQ== X-Received: by 2002:a17:902:ac88:: with SMTP id h8mr37601390plr.12.1562097801166; Tue, 02 Jul 2019 13:03:21 -0700 (PDT) X-Google-Smtp-Source: APXvYqxtoRhYyZmCaxHhvdyOZoO7ejF7TSsVRCMVcezdrDRZOgrUS0IwffkCi7uHQMj0NGTbEPJ3 X-Received: by 2002:a17:902:ac88:: with SMTP id h8mr37601333plr.12.1562097800371; Tue, 02 Jul 2019 13:03:20 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1562097800; cv=none; d=google.com; s=arc-20160816; b=PQKKWa0+Y5XBZL//HGGYYDvu8l3voqscJw7+3XuccAQfKEh45FWSFVOx+fBEVo3NL6 nm1p7fHqR0tv7M0dWJRNxa8A+mIIs+hxk3XOfl+LJqm9bk0iq82uXwA6mWZy7L9zrAD+ rQzZcldXIQWu//Q55G38tNLXF8c4sxNWEjO2RGNSAzCQtuJef8yywdM+z8vh+998ZVBz lIP/pGp4/A+gp94qftS0jIxLVy5qcye4U+BTZgpjUg8bXsTaxXoWdyg8tsbCUWkS1QlO tDP7bP1JJYkQGeY/HOTLlEP59aMDVqrBtnscRj3US7CO5MbGtwn2eZJ5Q+omokSBP9I1 R0wQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:subject:cc:to:from:date:dkim-signature; bh=Kcly/tuUbH1oIMLuOpvBwc3nXKhDlCKcUqNazXXJwlI=; b=S9fAcdIKhjTghR0ThEYGGsBg8qCw3SLHIWg3EEzuXCIu0K5LgBgumWU3NKdWqb8mGU 7QFOQVGo2lo+oT1kT4ecDNIiRSesDHzNDLMI641j6MoZUjTsU07EdSY+A2iP9/2STo4t dvkgAJAY6nv4+8+69BJOHIr1fKDnsNvojKfN+hVbakgFWULbn4+vY2pl2f7OyNOh2QzC OWTY2Rh6r2j8fqGHsANxbpYluD7lKCTNogyBepQNTlV4gkualAt54FTqK4/gwX6Kr4dL hUlyXCC989+B+spSBZdhjNIuWQLs8HS5bsiRZTWhxm9Jl3cPxuSRGLkipS5UTgdnEzAw Omlw== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@kernel.org header.s=default header.b=Tiln9LxM; spf=pass (google.com: domain of akpm@linux-foundation.org designates 198.145.29.99 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org Received: from mail.kernel.org (mail.kernel.org. [198.145.29.99]) by mx.google.com with ESMTPS id t14si15510110pfq.88.2019.07.02.13.03.20 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 02 Jul 2019 13:03:20 -0700 (PDT) Received-SPF: pass (google.com: domain of akpm@linux-foundation.org designates 198.145.29.99 as permitted sender) client-ip=198.145.29.99; Authentication-Results: mx.google.com; dkim=pass header.i=@kernel.org header.s=default header.b=Tiln9LxM; spf=pass (google.com: domain of akpm@linux-foundation.org designates 198.145.29.99 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org Received: from akpm3.svl.corp.google.com (unknown [104.133.8.65]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 662352184C; Tue, 2 Jul 2019 20:03:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1562097799; bh=kyfxYTDfXVVYVh+jLp8SPqoH6e+/on1CISn5rmKjOZ0=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=Tiln9LxMX1fNAo2/Ddp+J6EQL7IwtJ9uvLaA5tNsAMv7HWx786TfZZ+Zg2iwEa3zy 7DBc6NmB8eX7vXDjNIm9YVca7qmERe9+BWTzyahQE+3k8jNzrBotulWcBmvPHIX2uk qZiUwdYXD/LKMhpngm7ibkztyOQiF7ErCvRr6OuA= Date: Tue, 2 Jul 2019 13:03:18 -0700 From: Andrew Morton To: Waiman Long Cc: Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Alexander Viro , Jonathan Corbet , Luis Chamberlain , Kees Cook , Johannes Weiner , Michal Hocko , Vladimir Davydov , linux-mm@kvack.org, linux-doc@vger.kernel.org, linux-fsdevel@vger.kernel.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, Roman Gushchin , Shakeel Butt , Andrea Arcangeli Subject: Re: [PATCH] mm, slab: Extend slab/shrink to shrink all the memcg caches Message-Id: <20190702130318.39d187dc27dbdd9267788165@linux-foundation.org> In-Reply-To: <20190702183730.14461-1-longman@redhat.com> References: <20190702183730.14461-1-longman@redhat.com> X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.32; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit 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, 2 Jul 2019 14:37:30 -0400 Waiman Long wrote: > Currently, a value of '1" is written to /sys/kernel/slab//shrink > file to shrink the slab by flushing all the per-cpu slabs and free > slabs in partial lists. This applies only to the root caches, though. > > Extends this capability by shrinking all the child memcg caches and > the root cache when a value of '2' is written to the shrink sysfs file. Why? Please fully describe the value of the proposed feature to or users. Always. > > ... > > --- a/Documentation/ABI/testing/sysfs-kernel-slab > +++ b/Documentation/ABI/testing/sysfs-kernel-slab > @@ -429,10 +429,12 @@ KernelVersion: 2.6.22 > Contact: Pekka Enberg , > Christoph Lameter > Description: > - The shrink file is written when memory should be reclaimed from > - a cache. Empty partial slabs are freed and the partial list is > - sorted so the slabs with the fewest available objects are used > - first. > + A value of '1' is written to the shrink file when memory should > + be reclaimed from a cache. Empty partial slabs are freed and > + the partial list is sorted so the slabs with the fewest > + available objects are used first. When a value of '2' is > + written, all the corresponding child memory cgroup caches > + should be shrunk as well. All other values are invalid. One would expect this to be a bitfield, like /proc/sys/vm/drop_caches. So writing 3 does both forms of shrinking. Yes, it happens to be the case that 2 is a superset of 1, but what about if we add "4"?