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=-10.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,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 C7DFFC433DF for ; Tue, 4 Aug 2020 14:24:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A887D22BED for ; Tue, 4 Aug 2020 14:24:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1596551057; bh=5Z8Kopbxi7aEpHCihK5wFEwoJps5FrOJMRK80kP90m0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=WnFVsnQNPDIQYs3r1T3eCPWBQtrGjfCdHd31j6hcVdjYwOjeqPF23KHyy63u0Wni1 nngwRlSISIVGyoUOLMSulr95cqnPPzd6Qwq108KQ82iPie7/+aiHmbm21lGQklBgnL Kimn7GHjy4CjijwSNQw9/R+Ji5RTPNt9aatezH2o= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728962AbgHDOYQ (ORCPT ); Tue, 4 Aug 2020 10:24:16 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56560 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728948AbgHDOYM (ORCPT ); Tue, 4 Aug 2020 10:24:12 -0400 Received: from mail-qk1-x741.google.com (mail-qk1-x741.google.com [IPv6:2607:f8b0:4864:20::741]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 324ABC06174A; Tue, 4 Aug 2020 07:24:12 -0700 (PDT) Received: by mail-qk1-x741.google.com with SMTP id q128so6152343qkd.2; Tue, 04 Aug 2020 07:24:12 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=dd6Yl/t8idEhFl//6BuOYRHIHDUL8327gbR9zAH7VII=; b=PbNtTay4aqskHx+9NdhxFZehseF/nhdVcF1l3LZK2X9Y8rjBIVIVTDfdX8+RRTLJeA BEn0NuZaG0ByYr4U3wvLnPB7jioK1XTMQ6VXC8FaMiqEl/YUDMz+n+HkmOx+vfb2ERLw Bsxz656teytYovIbCIZhVSQF7E27WRL1BclCtwCXKXV7OUnCwsJgfbtH0opD9dyDoQds vce0WCBMuT6d7fOOWazK3E9sDVc/K0ofrF2lx5G9fO6IrKNQzDrFaybad62VDPcb2zjT RhgOjhM/0TMCDzmyYDzb4id3XkOqE5xdYWcc82BnHGJTZwGPT5MiRm+LLr7Xlvhzjl6W F0wQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:from:to:cc:subject:message-id :references:mime-version:content-disposition:in-reply-to; bh=dd6Yl/t8idEhFl//6BuOYRHIHDUL8327gbR9zAH7VII=; b=jMbijD4ZNTudqGrRuyjSUvjfBhcocYkX+HG/OPkLDYaPr8HvPlRSXXsZA5GMTx0nX5 ph9fIji7S/teC8B4AtgaQsYzPddvVbFFuFqM+s+n5b9QjUQSKTn0SrEBXNMCYOVEE3J2 f/iKdYYfcTPEjqvTVSLe0uvjTKe0jHaqRO0p/LRuwNzTwa2CGMHIvuY9WTjGeDlsV2Iv Tj+Rxdjaw+fOhe0OEwUdHHnap38Q7KW9q3kebi4NUJeaojvRpTBmk2kye9lN/3A6HrrR l9CZAxLeAd1bQVqC7XweWCOHgvG7u2kkyTYQSxIgRe9hWSbgBMwnA0FU9x6HFd6bNyIC opHA== X-Gm-Message-State: AOAM530k5Btlehzp8TbnWqprwPFrGbgwJPzvu/i3WHXXDUedJ9sSPamv 0T9Cts1PhxOATGS3esqomuw= X-Google-Smtp-Source: ABdhPJzQmpUK1CGTt/9F7/7OOwbjOHmbsjZjrMdamoMxD7JzhRhkXt/EzrnWxr2DlJs+sh5kwNLiNw== X-Received: by 2002:a37:614:: with SMTP id 20mr20958000qkg.456.1596551051224; Tue, 04 Aug 2020 07:24:11 -0700 (PDT) Received: from localhost ([2620:10d:c091:480::1:d024]) by smtp.gmail.com with ESMTPSA id d8sm25642978qtr.12.2020.08.04.07.24.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 04 Aug 2020 07:24:10 -0700 (PDT) Date: Tue, 4 Aug 2020 10:24:09 -0400 From: Tejun Heo To: Chengming Zhou Cc: axboe@kernel.dk, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] iocost: Only inc nr_shortages when have io waited Message-ID: <20200804142409.GB4819@mtj.thefacebook.com> References: <20200801170021.76756-1-zhouchengming@bytedance.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200801170021.76756-1-zhouchengming@bytedance.com> Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Sun, Aug 02, 2020 at 01:00:21AM +0800, Chengming Zhou wrote: > The last else branch of current code may have not io waited in iocg, > in which case we should not inc nr_shortages, or the device vrate > will speed up even this iocg is not shortage of vtime. > > Signed-off-by: Chengming Zhou > --- > block/blk-iocost.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/block/blk-iocost.c b/block/blk-iocost.c > index 86ba6fd254e1..ce68b5749364 100644 > --- a/block/blk-iocost.c > +++ b/block/blk-iocost.c > @@ -1485,7 +1485,7 @@ static void ioc_timer_fn(struct timer_list *timer) > __propagate_active_weight(iocg, iocg->weight, > new_inuse); > } > - } else { > + } else if (waitqueue_active(&iocg->waitq)) { This is intentional. Shortage doesn't necessarily mean that there are waiters right now. If there are cgroups which don't have enough headroom to donate and the device is hitting the latency targets, it makes sense to ramp up vrate as those cgroups are likely to get throttled. Thanks. -- tejun