From owner-freebsd-hackers@freebsd.org Thu Apr 16 16:08:37 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 6AE362C093F for ; Thu, 16 Apr 2020 16:08:37 +0000 (UTC) (envelope-from freebsd-rwg@gndrsh.dnsmgr.net) Received: from gndrsh.dnsmgr.net (br1.CN84in.dnsmgr.net [69.59.192.140]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 4934042jFgz3CVr for ; Thu, 16 Apr 2020 16:08:36 +0000 (UTC) (envelope-from freebsd-rwg@gndrsh.dnsmgr.net) Received: from gndrsh.dnsmgr.net (localhost [127.0.0.1]) by gndrsh.dnsmgr.net (8.13.3/8.13.3) with ESMTP id 03GG8Y95046250; Thu, 16 Apr 2020 09:08:34 -0700 (PDT) (envelope-from freebsd-rwg@gndrsh.dnsmgr.net) Received: (from freebsd-rwg@localhost) by gndrsh.dnsmgr.net (8.13.3/8.13.3/Submit) id 03GG8Ym1046249; Thu, 16 Apr 2020 09:08:34 -0700 (PDT) (envelope-from freebsd-rwg) From: "Rodney W. Grimes" Message-Id: <202004161608.03GG8Ym1046249@gndrsh.dnsmgr.net> Subject: Re: fsck parallel check In-Reply-To: To: Wojciech Puchar Date: Thu, 16 Apr 2020 09:08:34 -0700 (PDT) CC: freebsd-hackers@freebsd.org X-Mailer: ELM [version 2.4ME+ PL121h (25)] MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=US-ASCII X-Rspamd-Queue-Id: 4934042jFgz3CVr X-Spamd-Bar: + Authentication-Results: mx1.freebsd.org; dkim=none; dmarc=none; spf=none (mx1.freebsd.org: domain of freebsd-rwg@gndrsh.dnsmgr.net has no SPF policy when checking 69.59.192.140) smtp.mailfrom=freebsd-rwg@gndrsh.dnsmgr.net X-Spamd-Result: default: False [1.34 / 15.00]; ARC_NA(0.00)[]; NEURAL_HAM_MEDIUM(-0.34)[-0.336,0]; FROM_HAS_DN(0.00)[]; TO_DN_SOME(0.00)[]; MIME_GOOD(-0.10)[text/plain]; RCVD_TLS_LAST(0.00)[]; DMARC_NA(0.00)[dnsmgr.net]; AUTH_NA(1.00)[]; TO_MATCH_ENVRCPT_SOME(0.00)[]; RCPT_COUNT_TWO(0.00)[2]; NEURAL_SPAM_LONG(0.75)[0.745,0]; R_SPF_NA(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; R_DKIM_NA(0.00)[]; MIME_TRACE(0.00)[0:+]; ASN(0.00)[asn:13868, ipnet:69.59.192.0/19, country:US]; MID_RHS_MATCH_FROM(0.00)[]; IP_SCORE(0.03)[ip: (0.13), ipnet: 69.59.192.0/19(0.06), asn: 13868(0.03), country: US(-0.05)]; RCVD_COUNT_TWO(0.00)[2] 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, 16 Apr 2020 16:08:37 -0000 > can it be changed? It *could* be changed, but the more important question is *should* it be changed. See below. > fsck checks in sequence all filesystems with 6-th field in /etc/fstab > equal 1, and in parallel all with 6-th field equal 2 but one process per > disk. > > This is right if you have magnetic disks. checking 2 partitions in > parallel on one physical disk is bad idea. > > But it is very good idea to do this on SSD with multiple partitions. Why do you state that? >From my perspective it is more that one thread is "good enough": fsck should be I/O bound, more threads on a single ssd should just lead to I/O queue building and no net reduction in time to complete. Do you have some data that contridicts that? > > Can it be changed ? See above. > > If not - i can write a fix for this (option settable in fstab). -- Rod Grimes rgrimes@freebsd.org