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 X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A8E29C1B0F1 for ; Tue, 19 Jun 2018 22:19:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 63EF120836 for ; Tue, 19 Jun 2018 22:19:19 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=joelfernandes.org header.i=@joelfernandes.org header.b="wKKJhp7F" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 63EF120836 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=joelfernandes.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S936117AbeFSWTR (ORCPT ); Tue, 19 Jun 2018 18:19:17 -0400 Received: from mail-pg0-f66.google.com ([74.125.83.66]:40723 "EHLO mail-pg0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S935912AbeFSWTP (ORCPT ); Tue, 19 Jun 2018 18:19:15 -0400 Received: by mail-pg0-f66.google.com with SMTP id w8-v6so496037pgp.7 for ; Tue, 19 Jun 2018 15:19:15 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=joelfernandes.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=+sERxtNUIBI5JSphQbyJXa+JULTDg0FWPDhfOqQu4O4=; b=wKKJhp7F73oCsiZErGNLU6/jvGCvGdFqJrMNvgZuD73PLQtt5ru/q/vn0dyMBhvSaZ +a4+3OL0kLRox6LJywg/qCUfWgKnFctwG2bNc+MbtkV/OfOKGolNRJe+Y7+FTdfZSAkk fMMoIp3r0N/oK6xGnOYIefX5I++EL6J7SD0a4= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=+sERxtNUIBI5JSphQbyJXa+JULTDg0FWPDhfOqQu4O4=; b=qcI0MB6wigpxAIZ+/XfS3zfr9Vje61p6vk7/LahkMA1UydsHFtnnPO4DStSVw/o8oJ qTL9Xjx59ibI/+L/OrW2S2hP7WLDZxCXafpABinYk03ZYtvYZ0uiFCsqzGdM81EOmt6O O6fpWADOdhUn+NGetAcDjltSdB2u6XTz1MqxAifP1FKML4TnHtHkvGOkn2XjTdV1mEBO GoUhCrddiRPdq0YGmHV5BY6J0vWZJG/iHt10Tfoeef8CuCH3cuQSDxCvDXFSgH3Tr597 PzKL2FmFBXTvQb2FdW5KMF0epSKbt1fz3VTomeY/0bVuleIdKQdYukdKvhyoULmkemKa UCDA== X-Gm-Message-State: APt69E1ZaIpeMjUAzT8xbZhowIqQDl2ruBKo5w3SGT9e2zawOs5zjZ0Z Sbd72jHbFmSt+J2b1lEl6kphjQ== X-Google-Smtp-Source: ADUXVKKM5MshOMkPdQc1/kRxokh6Bq8TOpBcn7thmRGsN2tnUTJu9WhRbfREronWM1KVIujC1pvjcQ== X-Received: by 2002:a62:4e07:: with SMTP id c7-v6mr20064848pfb.149.1529446754863; Tue, 19 Jun 2018 15:19:14 -0700 (PDT) Received: from localhost ([2620:0:1000:1600:3122:ea9c:d178:eb]) by smtp.gmail.com with ESMTPSA id s75-v6sm912543pfj.125.2018.06.19.15.19.14 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Tue, 19 Jun 2018 15:19:14 -0700 (PDT) Date: Tue, 19 Jun 2018 15:19:14 -0700 From: Joel Fernandes To: "Paul E. McKenney" Cc: linux-kernel@vger.kernel.org, kernel-team@android.com, Josh Triplett , Lai Jiangshan , Mathieu Desnoyers , Steven Rostedt , Byungchul Park Subject: Re: [PATCH 1/2] rcu: Assign higher priority to RCU threads if its rcutorture Message-ID: <20180619221914.GB41539@joelaf.mtv.corp.google.com> References: <20180619062215.221564-1-joel@joelfernandes.org> <20180619063421.GA221670@joelaf.mtv.corp.google.com> <20180619160024.GI3593@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180619160024.GI3593@linux.vnet.ibm.com> User-Agent: Mutt/1.9.2 (2017-12-15) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jun 19, 2018 at 09:00:24AM -0700, Paul E. McKenney wrote: > On Mon, Jun 18, 2018 at 11:34:21PM -0700, Joel Fernandes wrote: > > On Mon, Jun 18, 2018 at 11:22:14PM -0700, Joel Fernandes wrote: > > > From: "Joel Fernandes (Google)" > > > > > > rcutorture boost tests fail even with CONFIG_RCU_BOOST set because > > > rcutorture's threads are equal priority to the default RCU kthreads (RT > > > class with priority of 1). > > > > Sorry for the weird subject line, I meant "rcu: Assign higher prio if > > rcutorture is built into kernel". I have included the patch with the subject > > line fixed up below (if you prefer to take that instead). > > > > Also one question, incase rcutorture is a module, we can't raise the priority > > of the kthreads because it would be too late to do at module load time. In > > this case, do you have any ideas on what we can do? I was thinking we can > > access the kernel command line from within rcutorture module and check if > > 'rcutree.kthread_prio' was passed. And if it is and isn't sufficiently high, > > then we avoid testing boost feature at all (and print a nice message telling > > the user about the issue). > > I do like the idea of checking and printing the message in this case. Cool, I used this approach in the series I just sent. I agree its good to report it. > Another alternative would be to allow rcutree.kthread_prio to be changed > at runtime. But one caution: rcutree.kthread_prio applies to a number > of kthreads, not just the boost kthreads, so this approach might have > some unwelcome side-effects. Yes, I was trying to avoid those complexities just because of rcutorture. > > OTOH, we can just let rcutorture module loaders fail the test if you feel > > very few automation tests do the module loading way of rcutorture and so a > > boost test failure there is tolerable. For me, I will likely be running > > rcutorture only as a built-in so I am Ok with not special casing it within > > rcutorture. > > I don't know of anyone using the module-loading approach. Probably > someone somewhere does it from time to time, though. Oh Ok :). Then I guess the warning print from rcutorture is sufficient as I did. thanks! - Joel