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=-2.5 required=3.0 tests=MAILING_LIST_MULTI,SPF_PASS, USER_AGENT_MUTT autolearn=ham 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 E5791ECDFAA for ; Mon, 16 Jul 2018 09:12:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8F7BB208FC for ; Mon, 16 Jul 2018 09:12:28 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8F7BB208FC Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729810AbeGPJix (ORCPT ); Mon, 16 Jul 2018 05:38:53 -0400 Received: from mx2.suse.de ([195.135.220.15]:59936 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727022AbeGPJiw (ORCPT ); Mon, 16 Jul 2018 05:38:52 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 4FA41AE4C; Mon, 16 Jul 2018 09:12:24 +0000 (UTC) Date: Mon, 16 Jul 2018 11:12:22 +0200 From: Michal Hocko To: Dave Chinner Cc: James Bottomley , Linus Torvalds , Matthew Wilcox , Waiman Long , Al Viro , Jonathan Corbet , "Luis R. Rodriguez" , Kees Cook , Linux Kernel Mailing List , linux-fsdevel , linux-mm , "open list:DOCUMENTATION" , Jan Kara , Paul McKenney , Andrew Morton , Ingo Molnar , Miklos Szeredi , Larry Woodman , "Wangkai (Kevin,C)" Subject: Re: [PATCH v6 0/7] fs/dcache: Track & limit # of negative dentries Message-ID: <20180716091222.GI17280@dhcp22.suse.cz> References: <18c5cbfe-403b-bb2b-1d11-19d324ec6234@redhat.com> <1531336913.3260.18.camel@HansenPartnership.com> <4d49a270-23c9-529f-f544-65508b6b53cc@redhat.com> <1531411494.18255.6.camel@HansenPartnership.com> <20180712164932.GA3475@bombadil.infradead.org> <1531416080.18255.8.camel@HansenPartnership.com> <1531425435.18255.17.camel@HansenPartnership.com> <20180713003614.GW2234@dastard> <20180716090901.GG17280@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180716090901.GG17280@dhcp22.suse.cz> User-Agent: Mutt/1.10.0 (2018-05-17) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon 16-07-18 11:09:01, Michal Hocko wrote: > On Fri 13-07-18 10:36:14, Dave Chinner wrote: > [...] > > By limiting the number of negative dentries in this case, internal > > slab fragmentation is reduced such that reclaim cost never gets out > > of control. While it appears to "fix" the symptoms, it doesn't > > address the underlying problem. It is a partial solution at best but > > at worst it's another opaque knob that nobody knows how or when to > > tune. > > Would it help to put all the negative dentries into its own slab cache? We couldn't http://lkml.kernel.org/r/20180714173516.uumlhs4wgfgrlc32@devuan Sorry I haven't noticed the other line of discussion -- Michal Hocko SUSE Labs