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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id CF8E4C433F5 for ; Sat, 21 May 2022 23:47:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:Reply-To:List-Subscribe:List-Help: List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=nf3+Ds+amsDamFo18U37J/VBHWL+xF3Oxl1qtZoIhQk=; b=a4tO1HSFdXxLW7 YVC89iqJogKzo5QcPIr9N6JZH2xe/jqVVd7J9eZrmtnxUrhSDSpwFOvcMANdyQx8rQHCBNaxBMfZ7 PKn0cHiWgA8i/nRcHrL7X7S88G8QNOnw2MHE5ICiPu4W7j7W0sIRRKLLPqlf/o8tU1M+JCrANjkC5 QxdwKES4GHwoevPLUELQz9qmEphBzVIfLA9rRLsQaou4Ot/KbH3/0nna8IkzxaFlhJVwWOYvgETXL nLKAyNhpQGlxPk908PJOrKCQrFpabSnTgQRdkmVZFf/YMfdZxyVMqQFLZpHU3rFksiCvq0qEJhk1x Kw1ajMhoNimK1f3iQKRA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nsYni-000AEr-8q; Sat, 21 May 2022 23:46:26 +0000 Received: from ams.source.kernel.org ([2604:1380:4601:e00::1]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1nsYne-000ADv-37 for linux-arm-kernel@lists.infradead.org; Sat, 21 May 2022 23:46:23 +0000 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id E704AB8077E; Sat, 21 May 2022 23:46:17 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7088EC385A9; Sat, 21 May 2022 23:46:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1653176776; bh=ZvwJRsmyPHVu6xMhRrUXxcn+midJndmIlbuFTRbahrQ=; h=Date:From:To:Cc:Subject:Reply-To:References:In-Reply-To:From; b=XNscoE2xqCQNZy+sn84caROY4Pxn5GkYOAAbzVz5+lbHEEml6WVMqBNgkiou73QwX Lt7PM5eAxLu5xtIqrEwYC3h4rtDFGAWkntf56M+7gocu+qFwcz85a7NpmqDl2nDnJk IDRdGAKKBpu4Pmk4csxXGDhkU3axPoqKq1AySe+y9IZHoNb3U/ojJBfFrqYlqp7SF4 xWRohg+uDIJrnkQApg+mcNZC/wLCcQI8lM+yAh2v89GwMdmw+5kV0mvCOvEWeaWVh2 N49aNlCAZrVJ6xkaTpiC9dx5IVqXnjbLCWroX7xKJyHK/4RdzRJF9Z40CeUtNt7vEc w4TejJZKiszbg== Received: by paulmck-ThinkPad-P17-Gen-1.home (Postfix, from userid 1000) id 0C41A5C034F; Sat, 21 May 2022 16:46:16 -0700 (PDT) Date: Sat, 21 May 2022 16:46:16 -0700 From: "Paul E. McKenney" To: Stefan Wahren Cc: Marcelo Tosatti , Andrew Morton , Nicolas Saenz Julienne , Borislav Petkov , Minchan Kim , Matthew Wilcox , Mel Gorman , Juri Lelli , Thomas Gleixner , Sebastian Andrzej Siewior , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Linux ARM , Phil Elwell , regressions@lists.linux.dev, riel@surriel.com, viro@zeniv.linux.org.uk Subject: Re: vchiq: Performance regression since 5.18-rc1 Message-ID: <20220521234616.GO1790663@paulmck-ThinkPad-P17-Gen-1> References: <77d6d498-7dd9-03eb-60f2-d7e682bb1b20@i2se.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <77d6d498-7dd9-03eb-60f2-d7e682bb1b20@i2se.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220521_164622_455094_EFBCBCED X-CRM114-Status: GOOD ( 21.91 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: paulmck@kernel.org Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Sun, May 22, 2022 at 01:22:00AM +0200, Stefan Wahren wrote: > Hi, > = > while testing the staging/vc04_services/interface/vchiq_arm driver with my > Raspberry Pi 3 B+ (multi_v7_defconfig) i noticed a huge performance > regression since [ff042f4a9b050895a42cae893cc01fa2ca81b95c] mm: > lru_cache_disable: replace work queue synchronization with synchronize_rcu > = > Usually i run "vchiq_test -f 1" to see the driver is still working [1]. > = > Before commit: > = > real=A0=A0=A0 0m1,500s > user=A0=A0=A0 0m0,068s > sys=A0=A0=A0 0m0,846s > = > After commit: > = > real=A0=A0=A0 7m11,449s > user=A0=A0=A0 0m2,049s > sys=A0=A0=A0 0m0,023s > = > Best regards > = > [1] - https://github.com/raspberrypi/userland Please feel free to try the patch shown below. Or the pair of patches from Rik here: https://lore.kernel.org/lkml/20220218183114.2867528-2-riel@surriel.com/ https://lore.kernel.org/lkml/20220218183114.2867528-3-riel@surriel.com/ There is work ongoing to produce something better, but ongoing slowly. Especially my part of that work. Thanx, Paul ------------------------------------------------------------------------ >From paulmck@kernel.org Mon Feb 14 11:05:49 2022 Date: Mon, 14 Feb 2022 11:05:49 -0800 From: "Paul E. McKenney" To: clm@fb.com Cc: riel@surriel.com, viro@zeniv.linux.org.uk, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, kernel-team@fb.com Subject: [PATCH RFC fs/namespace] Make kern_unmount() use synchronize_rcu_expedited() Message-ID: <20220214190549.GA2815154@paulmck-ThinkPad-P17-Gen-1> Reply-To: paulmck@kernel.org MIME-Version: 1.0 Content-Type: text/plain; charset=3Dus-ascii Content-Disposition: inline Status: RO Content-Length: 1036 Lines: 32 Experimental. Not for inclusion. Yet, anyway. Freeing large numbers of namespaces in quick succession can result in a bottleneck on the synchronize_rcu() invoked from kern_unmount(). This patch applies the synchronize_rcu_expedited() hammer to allow further testing and fault isolation. Hey, at least there was no need to change the comment! ;-) Cc: Alexander Viro Cc: Cc: Not-yet-signed-off-by: Paul E. McKenney --- namespace.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/namespace.c b/fs/namespace.c index 40b994a29e90d..79c50ad0ade5b 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -4389,7 +4389,7 @@ void kern_unmount(struct vfsmount *mnt) /* release long term mount so mount point can be released */ if (!IS_ERR_OR_NULL(mnt)) { real_mount(mnt)->mnt_ns =3D NULL; - synchronize_rcu(); /* yecchhh... */ + synchronize_rcu_expedited(); /* yecchhh... */ mntput(mnt); } } _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel