From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ig0-f178.google.com (mail-ig0-f178.google.com [209.85.213.178]) by kanga.kvack.org (Postfix) with ESMTP id C41DB6B007E for ; Thu, 3 Mar 2016 00:40:05 -0500 (EST) Received: by mail-ig0-f178.google.com with SMTP id z8so10466719ige.0 for ; Wed, 02 Mar 2016 21:40:05 -0800 (PST) Received: from mail-pf0-x235.google.com (mail-pf0-x235.google.com. [2607:f8b0:400e:c00::235]) by mx.google.com with ESMTPS id u98si3068572ioi.74.2016.03.02.21.40.05 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 02 Mar 2016 21:40:05 -0800 (PST) Received: by mail-pf0-x235.google.com with SMTP id 63so8250046pfe.3 for ; Wed, 02 Mar 2016 21:40:05 -0800 (PST) Date: Thu, 3 Mar 2016 14:41:24 +0900 From: Sergey Senozhatsky Subject: Re: How to avoid printk() delay caused by cond_resched() ? Message-ID: <20160303054124.GA411@swordfish> References: <201603022101.CAH73907.OVOOMFHFFtQJSL@I-love.SAKURA.ne.jp> <20160302133810.GB22171@pathway.suse.cz> <20160302143415.GB614@swordfish> <20160302160437.GA2307@quack.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160302160437.GA2307@quack.suse.cz> Sender: owner-linux-mm@kvack.org List-ID: To: Jan Kara Cc: Sergey Senozhatsky , Petr Mladek , Tetsuo Handa , jack@suse.com, tj@kernel.org, kyle@kernel.org, davej@codemonkey.org.uk, calvinowens@fb.com, akpm@linux-foundation.org, linux-mm@kvack.org, mhocko@kernel.org On (03/02/16 17:04), Jan Kara wrote: > On Wed 02-03-16 23:34:15, Sergey Senozhatsky wrote: > > > I am looking forward to have the console printing offloaded > > > into the workqueues. Then printk() will become consistently > > > "fast" operation and will cause less surprises like this. > > > > I'm all for it. I need this rework badly. If Jan is too busy at > > the moment, which I surely can understand, then I'll be happy to > > help ("pick up the patches". please, don't get me wrong). > > So I'm rather busy with other stuff currently so if you can pick up my > patches and finish them, it would be good. I think I have addressed all the > comments you had to the previous version, except for handling the case > where all the workers are too busy - maybe using a dedicated workqueue with > a rescueue worker instead of system_wq would solve this issue. > > I've sent the current version of patches I have to you including the patch > 3/3 which I use for debugging and testing whether the async printing really > helps avoiding softlockups. great, thank you! will take a look. and yes, I was thinking about using printk's own workqueue with a rescue thread bit set (Petr Mladek also proposed this). -ss -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org