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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 736A1C433F5 for ; Wed, 29 Sep 2021 08:06:27 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id F279A613C8 for ; Wed, 29 Sep 2021 08:06:26 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org F279A613C8 Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id 68A96940014; Wed, 29 Sep 2021 04:06:26 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 63B76940011; Wed, 29 Sep 2021 04:06:26 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 52984940014; Wed, 29 Sep 2021 04:06:26 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0025.hostedemail.com [216.40.44.25]) by kanga.kvack.org (Postfix) with ESMTP id 4256E940011 for ; Wed, 29 Sep 2021 04:06:26 -0400 (EDT) Received: from smtpin05.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 0082718256736 for ; Wed, 29 Sep 2021 08:06:25 +0000 (UTC) X-FDA: 78639878772.05.91E8308 Received: from smtp-out1.suse.de (smtp-out1.suse.de [195.135.220.28]) by imf14.hostedemail.com (Postfix) with ESMTP id 8E7F5600198C for ; Wed, 29 Sep 2021 08:06:25 +0000 (UTC) Received: from relay1.suse.de (relay1.suse.de [149.44.160.133]) by smtp-out1.suse.de (Postfix) with ESMTP id 79107223AA; Wed, 29 Sep 2021 08:06:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1632902784; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=TSI5m2XtJxwQsHbZ7fT2hgL1JimUqhFMlSOa0hMeAqE=; b=nQ3zyjNRAQHSP7HZvghcO8YhihnkTugPkyO4+m1D1AtVucXIcbIn85IkBuMPrCbZ1Zla1K hcrft2nq4jFNhlnTX2AYvua+B3k5AGCOoHBP48VjH6uMHEyXMiUO79tiANKXW9eROrUGZw p+7+r9TLr8JQA4tFm8gjL1iTgzkAjWQ= Received: from suse.cz (unknown [10.100.201.86]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by relay1.suse.de (Postfix) with ESMTPS id 45AAC25D50; Wed, 29 Sep 2021 08:06:24 +0000 (UTC) Date: Wed, 29 Sep 2021 10:06:23 +0200 From: Michal Hocko To: Sultan Alsawaf Cc: Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm: vmscan: Replace shrinker_rwsem trylocks with SRCU protection Message-ID: References: <20210927074823.5825-1-sultan@kerneltoast.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 8E7F5600198C X-Stat-Signature: ghh3bdyeip16k89izjz9z7ckz1ksa3iw Authentication-Results: imf14.hostedemail.com; dkim=pass header.d=suse.com header.s=susede1 header.b=nQ3zyjNR; dmarc=pass (policy=quarantine) header.from=suse.com; spf=pass (imf14.hostedemail.com: domain of mhocko@suse.com designates 195.135.220.28 as permitted sender) smtp.mailfrom=mhocko@suse.com X-HE-Tag: 1632902785-646272 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 Mon 27-09-21 09:53:59, Sultan Alsawaf wrote: > On Mon, Sep 27, 2021 at 10:36:36AM +0200, Michal Hocko wrote: > > Can you be more specific about those scenarios please? > > I see frequent tmpfs mounts/unmounts in Android which result in lots of > superblocks being created and destroyed, and each superblock has its own > shrinker. This is an important detail to mention in the changelog. Including some details about the scale of the problem. > > I have a vague recollection that this approach has been proposed in the > > past. Have you checked previous attempts? > > I wasn't aware that there were previous attempts. Is this [1] the previous > attempt you're thinking of? It seems like the thread just died out. Was the main > gripe that always enabling CONFIG_SRCU increased the kernel's size too much when > tinyfication was desired? There were more discussions. I have also found https://lore.kernel.org/lkml/1510609063-3327-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp My memory is quite dim and I do not have time to re-read those discussions again right now. But if I remember correctly the last one has died out because a deeper evaluation between the SRCU and rw semaphores was required. > Sultan > > [1] https://lore.kernel.org/all/153365347929.19074.12509495712735843805.stgit@localhost.localdomain/ -- Michal Hocko SUSE Labs