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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 858A1C433EF for ; Mon, 25 Oct 2021 11:14:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5B7EC60238 for ; Mon, 25 Oct 2021 11:14:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231221AbhJYLRO (ORCPT ); Mon, 25 Oct 2021 07:17:14 -0400 Received: from smtp-out2.suse.de ([195.135.220.29]:57836 "EHLO smtp-out2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230126AbhJYLRK (ORCPT ); Mon, 25 Oct 2021 07:17:10 -0400 Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out2.suse.de (Postfix) with ESMTP id 9C76C1FD3E; Mon, 25 Oct 2021 11:14:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_rsa; t=1635160487; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=sjZAyXn5jG+05FEG8DgYvyLSGFHH/9MVtCf4zkIY++g=; b=gllVaCmfzL00sjlkxuaCvvC70v7Z8amLhuSF5kZJvKfb9KyTe35OMWjvFIPgb3nf0Ukmr7 KCr10VcH9iIkf/bMuJbJKhtOxerUg+iDnR+kRKZ9jE5RW3K/79Yuurrh07s1usy7Xfr8Kv tvmrhT9CjclVbHj2bASVammD7H9PthM= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1635160487; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=sjZAyXn5jG+05FEG8DgYvyLSGFHH/9MVtCf4zkIY++g=; b=zAu9IqlhwXtOM/tGGUzDeaLgrqW5Hi+Zjhwt/RbTw180T47rI7QlHR+s09OzW1mml/wjRs crS2sS8LEJbsGmCw== Received: from quack2.suse.cz (unknown [10.100.224.230]) by relay2.suse.de (Postfix) with ESMTP id 71FCBA3B81; Mon, 25 Oct 2021 11:14:47 +0000 (UTC) Received: by quack2.suse.cz (Postfix, from userid 1000) id 4F1D01E0BFB; Mon, 25 Oct 2021 13:14:47 +0200 (CEST) Date: Mon, 25 Oct 2021 13:14:47 +0200 From: Jan Kara To: Paolo Valente Cc: Jan Kara , linux-block , Jens Axboe , Michal =?iso-8859-1?Q?Koutn=FD?= , 237826@studenti.unimore.it, 224833@studenti.unimore.it, Giacomo Guiduzzi <224804@studenti.unimore.it>, 238290@studenti.unimore.it, PAOLO CROTTI <204572@studenti.unimore.it> Subject: Re: [PATCH 0/8 v3] bfq: Limit number of allocated scheduler tags per cgroup Message-ID: <20211025111447.GB12157@quack2.suse.cz> References: <20211006164110.10817-1-jack@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Mon 25-10-21 09:58:11, Paolo Valente wrote: > > Il giorno 7 ott 2021, alle ore 18:33, Paolo Valente ha scritto: > >> Il giorno 6 ott 2021, alle ore 19:31, Jan Kara ha scritto: > >> > >> Hello! > >> > >> Here is the third revision of my patches to fix how bfq weights apply on cgroup > >> throughput and on throughput of processes with different IO priorities. Since > >> v2 I've added some more patches so that now IO priorities also result in > >> service differentiation (previously they had no effect on service > >> differentiation on some workloads similarly to cgroup weights). The last patch > >> in the series still needs some work as in the current state it causes a > >> notable regression (~20-30%) with dbench benchmark for large numbers of > >> clients. I've verified that the last patch is indeed necessary for the service > >> differentiation with the workload described in its changelog. As we discussed > >> with Paolo, I have also found out that if I remove the "waker has enough > >> budget" condition from bfq_select_queue(), dbench performance is restored > >> and the service differentiation is still good. But we probably need some > >> justification or cleaner solution than just removing the condition so that > >> is still up to discussion. But first seven patches already noticeably improve > >> the situation for lots of workloads so IMO they stand on their own and > >> can be merged regardless of how we go about the last patch. > >> > > > > Hi Jan, > > I have just one more (easy-to-resolve) doubt: you seem to have tested > > these patches mostly on the throughput side. Did you run a > > startup-latency test as well? I can run some for you, if you prefer > > so. Just give me a few days. > > > > We are finally testing your patches a little bit right now, for > regressions with our typical benchmarks ... Hum, strange I didn't get your previous email about benchmarks. You're right I didn't run startup-latency AFAIR. Now that you've started them, probably there's no big point in me queuing them as well. So thanks for the benchmarking :) Honza -- Jan Kara SUSE Labs, CR