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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no 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 DB395C433ED for ; Mon, 10 May 2021 19:56:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B524561019 for ; Mon, 10 May 2021 19:56:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231859AbhEJT55 (ORCPT ); Mon, 10 May 2021 15:57:57 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53036 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230342AbhEJT54 (ORCPT ); Mon, 10 May 2021 15:57:56 -0400 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 32ED6C061574 for ; Mon, 10 May 2021 12:56:51 -0700 (PDT) From: Thomas Gleixner DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1620676608; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=RnsCi4tsfX2EqkxQUyb5I4F/v2kHeUeGstf11LeuD24=; b=h4WDucZYAjALME2VAr4sUcDFtrwd+qDWQJUSNZ2QtDyfAZvGeKFxNJs4M/nvq+Ij/i1TPq m0u4HNhXDlodulnGSiA1lz4L5WpCUvtXn9aEOUHS4hHsEsC7e+krK/+cQ4mhmVzWWRYbob 3SHjf0Cgaqd4cxhkkMbgJ5rBiXatg4ligh0cdQQ54z6hNXqA1qWTVf21rRTF9oAgH0ABzU ++X1aHmFw5hnQqTsG085zuf5TbkgZQgCq5goHn4qtneGmiQmE+CB7BJejbcQJzGAye61+u 6GZySM/dR11ZQNLYUZOe4ueBafLA3kk37ErNDXrxeHf1dJeZCdLyhOJNbg1f4g== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1620676608; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=RnsCi4tsfX2EqkxQUyb5I4F/v2kHeUeGstf11LeuD24=; b=wYYj63iKrfnU2kzRsq94miAfEYRP4OHGf+WJ6KHq55/aU5EmGwZkJr5Z2xS/8n6OON87EX tT77+OdaPha9xzCQ== To: xuyihang , Ming Lei Cc: Peter Xu , Christoph Hellwig , Jason Wang , Luiz Capitulino , Linux Kernel Mailing List , "Michael S. Tsirkin" , minlei@redhat.com, liaochang1@huawei.com Subject: Re: Virtio-scsi multiqueue irq affinity In-Reply-To: <963e38b0-a7d6-0b13-af89-81b03028d1ae@huawei.com> References: <20190318062150.GC6654@xz-x1> <20190325050213.GH9149@xz-x1> <20190325070616.GA9642@ming.t460p> <20190325095011.GA23225@ming.t460p> <0f6c8a5f-ad33-1199-f313-53fe9187a672@huawei.com> <87zgx5l8ck.ffs@nanos.tec.linutronix.de> <963e38b0-a7d6-0b13-af89-81b03028d1ae@huawei.com> Date: Mon, 10 May 2021 21:56:48 +0200 Message-ID: <87wns6gy67.ffs@nanos.tec.linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Yihang, On Mon, May 10 2021 at 16:48, xuyihang wrote: > =E5=9C=A8 2021/5/8 20:26, Thomas Gleixner =E5=86=99=E9=81=93: >> Can you please provide a more detailed description of your system? >> - Kernel version > This experiment run on linux-4.19 Again. Please provide reports against the most recent mainline version and not against some randomly picked kernel variant. > If we make some change on this experiment: > > 1.=C2=A0 Make this RT application use less CPU time instead of 100%, the = problem > disappear. > > 2, If we change rq_affinity to 2, in order to avoid handle softirq on=20 > the same core of RT thread, the problem also disappear. However, this app= roach > result in about 10%-30% random write proformance deduction comparing > to rq_affinity =3D 1, since it may has better cache utilization. > echo 2 > /sys/block/sda/queue/rq_affinity > > Therefore, I want to exclude some CPU from managed irq on boot > parameter, Why has this realtime thread to run on CPU0 and cannot move to some other CPU? > which has simliar approach to 11ea68f553e2 ("genirq, sched/isolation:=20 > Isolate from handling managed interrupts"). Why can't you use the existing isolation mechanisms? Thanks, tglx