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=-2.5 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,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 6C963C43441 for ; Fri, 16 Nov 2018 15:18:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2AAB02087C for ; Fri, 16 Nov 2018 15:18:21 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=kernel-dk.20150623.gappssmtp.com header.i=@kernel-dk.20150623.gappssmtp.com header.b="kglCUr/W" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2AAB02087C Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=kernel.dk Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-block-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389961AbeKQBbH (ORCPT ); Fri, 16 Nov 2018 20:31:07 -0500 Received: from mail-io1-f66.google.com ([209.85.166.66]:40723 "EHLO mail-io1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728169AbeKQBbH (ORCPT ); Fri, 16 Nov 2018 20:31:07 -0500 Received: by mail-io1-f66.google.com with SMTP id r7-v6so17190212iog.7 for ; Fri, 16 Nov 2018 07:18:20 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.20150623.gappssmtp.com; s=20150623; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=Js3BmtMcu/8Ddx1lEHQ784GFTsGFd07w04MFcc6IQ8c=; b=kglCUr/WLjwZiQ0E2CZyJsgMBYZ0QG4zYdk3OkTyo71pEf4Hd7Y+BbZY4/IhjbcXxH HNe8y/hjNYUuSbg6a24PW8kvUhOh9UiyzaVcWxBfXgXwxe1q1A0D1YcuLsxieIUztpGF 9fxxaRPoLMtA3cEKwaLFfAKKAXC0sNo3dDjpmN6H2PsOHzAU50DPNU7KVqzT1DuBeewl bU4F++jvCGj1FKL+wB4vHefcq1MgXJZK/lnMs9hvnripIdcFtqFq3YEqn5u0I+DB773q t/fNRFP2x1PKeSlf4yuY2Q3dZ9Pet5298Wvp7OTuRRvXAHVJpHMgIHGcOckQfpW6AGvG Bp/g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=Js3BmtMcu/8Ddx1lEHQ784GFTsGFd07w04MFcc6IQ8c=; b=VlxY0OKh6r9NHzB9xf8XvcYfXwVZTddGUt8S6l2XBwKUH+d7yiZrCbA0T9E0D2QMGC uhzlgW3WgdWpi27sSrhsxftxdvhnZasDQiPKvbLBv/MCKV9lVd5m64jKWDlKpHdq7qhL Ed9eE5MlYCx3SLQsa3PONH4hJtcavDCO645p/oe1kjwr2vBZit86hO4p+MxjiK7R+Ygt 1itOg1HGOjljpG81Ke7o8cg7FnwVw9QKNGxBBgkFWdlctibYeFRyyb45NBWdUvO2oPMJ KpWimvz4lpenVFSFuG6XCttMvAiPmntJ+x8qmrNrJDFS4YkpxwrHm44vKdetqXDaKGUs mR6w== X-Gm-Message-State: AA+aEWbhCFvCGFNvDgT9kEjn3j3VqGCOQDy9nnGrxzLFdHF8m8VREU1R CrrkM37croj0NaYZbTFhkyH1ay5SxsQ= X-Google-Smtp-Source: AFSGD/WpB1SGoFYMsnX8xiGKMkqlAUPFkmi+l/FvaRuHsoP/8IcEPas64hlONe1R+/EQ20LW5PBbLw== X-Received: by 2002:a5e:c74d:: with SMTP id g13mr5210929iop.26.1542381499675; Fri, 16 Nov 2018 07:18:19 -0800 (PST) Received: from [192.168.1.56] ([216.160.245.98]) by smtp.gmail.com with ESMTPSA id 68-v6sm1489283itv.25.2018.11.16.07.18.18 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 16 Nov 2018 07:18:18 -0800 (PST) Subject: Re: [PATCH 03/11] blk-rq-qos: inline check for q->rq_qos functions To: Christoph Hellwig Cc: linux-block@vger.kernel.org, Josef Bacik References: <20181115195135.22812-1-axboe@kernel.dk> <20181115195135.22812-4-axboe@kernel.dk> <20181116083839.GE9023@infradead.org> From: Jens Axboe Message-ID: Date: Fri, 16 Nov 2018 08:18:17 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1 MIME-Version: 1.0 In-Reply-To: <20181116083839.GE9023@infradead.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On 11/16/18 1:38 AM, Christoph Hellwig wrote: > On Thu, Nov 15, 2018 at 12:51:27PM -0700, Jens Axboe wrote: >> Put the short code in the fast path, where we don't have any >> functions attached to the queue. This minimizes the impact on >> the hot path in the core code. > > This looks mechanically fine: > > Reviewed-by: Christoph Hellwig > > But since I seem to have missed the introduction of it - why do we need > multiple struct rq_qos per request to start with? This sort of stacking > seems rather odd and counter-productive, and the commit introducing > this code doesn't explain the rationale at all. Per request-queue, not per request. One would be iolatency, one would be wbt, etc. -- Jens Axboe