From owner-freebsd-hackers@freebsd.org Thu Jan 23 13:35:16 2020 Return-Path: Delivered-To: freebsd-hackers@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id 9DB631F2454 for ; Thu, 23 Jan 2020 13:35:16 +0000 (UTC) (envelope-from SRS0=hgVM=3M=quip.cz=000.fbsd@elsa.codelab.cz) Received: from elsa.codelab.cz (elsa.codelab.cz [94.124.105.4]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 483NYv4mPFz4dk2 for ; Thu, 23 Jan 2020 13:35:15 +0000 (UTC) (envelope-from SRS0=hgVM=3M=quip.cz=000.fbsd@elsa.codelab.cz) Received: from elsa.codelab.cz (localhost [127.0.0.1]) by elsa.codelab.cz (Postfix) with ESMTP id 1979A28416; Thu, 23 Jan 2020 14:35:14 +0100 (CET) Received: from illbsd.quip.test (ip-62-24-92-232.net.upcbroadband.cz [62.24.92.232]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by elsa.codelab.cz (Postfix) with ESMTPSA id 4F02928429; Thu, 23 Jan 2020 14:35:13 +0100 (CET) Subject: Re: slow directory operation on huge dirs To: Wojciech Puchar Cc: freebsd-hackers@freebsd.org References: From: Miroslav Lachman <000.fbsd@quip.cz> Message-ID: <9b426949-be87-106a-46c3-f1b6a2e5bb83@quip.cz> Date: Thu, 23 Jan 2020 14:35:13 +0100 User-Agent: Mozilla/5.0 (X11; FreeBSD amd64; rv:52.0) Gecko/20100101 Firefox/52.0 SeaMonkey/2.49.3 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 483NYv4mPFz4dk2 X-Spamd-Bar: ++++ Authentication-Results: mx1.freebsd.org; dkim=none; dmarc=none; spf=none (mx1.freebsd.org: domain of SRS0=hgVM=3M=quip.cz=000.fbsd@elsa.codelab.cz has no SPF policy when checking 94.124.105.4) smtp.mailfrom=SRS0=hgVM=3M=quip.cz=000.fbsd@elsa.codelab.cz X-Spamd-Result: default: False [4.06 / 15.00]; ARC_NA(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; FROM_HAS_DN(0.00)[]; TO_DN_SOME(0.00)[]; IP_SCORE(0.86)[ip: (0.35), ipnet: 94.124.104.0/21(0.17), asn: 42000(3.70), country: CZ(0.09)]; MIME_GOOD(-0.10)[text/plain]; RCVD_TLS_LAST(0.00)[]; DMARC_NA(0.00)[quip.cz]; AUTH_NA(1.00)[]; NEURAL_SPAM_MEDIUM(1.00)[0.996,0]; RCVD_COUNT_THREE(0.00)[3]; TO_MATCH_ENVRCPT_SOME(0.00)[]; RCPT_COUNT_TWO(0.00)[2]; RCVD_IN_DNSWL_NONE(0.00)[4.105.124.94.list.dnswl.org : 127.0.10.0]; NEURAL_SPAM_LONG(1.00)[1.000,0]; R_SPF_NA(0.00)[]; FORGED_SENDER(0.30)[000.fbsd@quip.cz,SRS0=hgVM=3M=quip.cz=000.fbsd@elsa.codelab.cz]; R_DKIM_NA(0.00)[]; MIME_TRACE(0.00)[0:+]; ASN(0.00)[asn:42000, ipnet:94.124.104.0/21, country:CZ]; FROM_NEQ_ENVFROM(0.00)[000.fbsd@quip.cz,SRS0=hgVM=3M=quip.cz=000.fbsd@elsa.codelab.cz]; MID_RHS_MATCH_FROM(0.00)[] X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 23 Jan 2020 13:35:16 -0000 Wojciech Puchar wrote on 2020/01/23 14:12: >>>> >>> nobody have idea what's the problem? >> >> Is it "just slow" or is your disk too busy? (iostat) > > no. disk is idle, system CPU load takes half of system (8 cores)! > >> >> Can it be that pre-cacheing on huge directory makes disk too busy >> because there is too much to read? > this part works fine. The problem begins where it's already cached. > > To get the problem you need BOTH of: > > - large maxvnodes like half million > - large directory (in order of 100000 files) I remember very similar problem with slow access of directories with 80 000+ files. It was always slow like frozen hell. There is some recommendation to avoid more than 10 000 of file entries in a directory. That is why filesystem caches or sessions in PHP must create more levels of subdirectories. I know you cannot control users of maildirs. I am not sure if this situation can be improved or not. Miroslav Lachman