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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 46500C001DF for ; Tue, 11 Jul 2023 15:43:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233235AbjGKPns (ORCPT ); Tue, 11 Jul 2023 11:43:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56584 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233459AbjGKPnJ (ORCPT ); Tue, 11 Jul 2023 11:43:09 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8C73A1736 for ; Tue, 11 Jul 2023 08:42:55 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 29D6B61529 for ; Tue, 11 Jul 2023 15:42:55 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 85158C433C9; Tue, 11 Jul 2023 15:42:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1689090174; bh=CTZv+uGsbkFWSSp5DdKL+xgjoPEBdNgMCK1onOOx54c=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=eLeUa+WyQpoyeGo78KyDh8kef3WEbVJrehkA3GZvnl0fS/N+KWtQ71NJeLdaeDjqL 8tImx++E8m4aA7L4gxSk3eNJ48P6PBS2A4VTIWIef+qVUgwaN1Q2yf+3BY43I8FqJ8 bkAa6n02SyMfKKSSrjT6FiVF1WpsuV3stzKLHKRQ5y09PXGhlCdm4vpcI0iorAoEPa KbxVl8Qf3/aZYiOkb6OCeEleJLpkQc4cThK6e/rQ5YtUjBM6OYssOJQ+i2XTJrRG84 1Jd+1pKOsDMzzvOHR4IflnvgabR1mQUEY6bePR5fOq98jCgMazn1mNHnOF1cRdP2Jt QeOFOK2Le/Uug== Date: Tue, 11 Jul 2023 08:42:54 -0700 From: "Darrick J. Wong" To: "Eugene K." Cc: linux-xfs@vger.kernel.org Subject: Re: XFS writing issue Message-ID: <20230711154254.GC108251@frogsfrogsfrogs> References: <583703ce-1515-a436-1f34-3386150a03c2@railglorg.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <583703ce-1515-a436-1f34-3386150a03c2@railglorg.net> Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org On Tue, Jul 11, 2023 at 05:31:13PM +0200, Eugene K. wrote: > Hello. > > During investigation of flapping performance problem, it was detected that > once a process writes big amount of data in a row, the filesystem focus on > this writing and no other process can perform any IO on this filesystem. > > We have noticed huge %iowait on software raid1 (mdraid) that runs on 2 SSD > drives - on every attempt to write more than 1GB. > > The issue happens on any server running 6.4.2, 6.4.0, 6.3.3, 6.2.12 kernel. > Upon investigating and testing it appeared that server IO performance can be > completely killed with a single command: > > #cat /dev/zero > ./removeme > > assuming the ~/removeme file resides on rootfs and rootfs is XFS. > > While running this, the server becomes so unresponsive that after ~15 > seconds it's not even possible to login via ssh! > > We did reproduce this on every machine with XFS as rootfs running mentioned > kernels. However, when we converted rootfs from XFS to EXT4(and btrfs), the > problem disappeared - with the same OS, same kernel binary, same hardware, > just using ext4 or btrfs instead of xfs. So use ext4. --D > Note. During the hang and being unresponsive, SSD drives are writing data at > expected performance. Just all the processes except the writing one hang. > >