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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 27567CDB465 for ; Mon, 16 Oct 2023 21:16:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233514AbjJPVQS (ORCPT ); Mon, 16 Oct 2023 17:16:18 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40282 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233282AbjJPVQP (ORCPT ); Mon, 16 Oct 2023 17:16:15 -0400 Received: from mail-pl1-f169.google.com (mail-pl1-f169.google.com [209.85.214.169]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D7EBFAC; Mon, 16 Oct 2023 14:16:13 -0700 (PDT) Received: by mail-pl1-f169.google.com with SMTP id d9443c01a7336-1c9e95aa02dso30812745ad.0; Mon, 16 Oct 2023 14:16:13 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1697490973; x=1698095773; h=content-transfer-encoding:in-reply-to:from:references:to :content-language:subject:user-agent:mime-version:date:message-id :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=lEhcuHiu2scOZP08dw+rF+hfx+bVpPniCecMP/FEFVg=; b=hIucgWl1ZWBatpFSMsBOWUeX7V1J+m9rJIJ7VoPvbZkkuXB05WJ4j7Ojnk1P6ENMId LUVjIF6vF20mHyjMlxfBHwENRORyF9v+8VojZPHi8/Imaw5qWFcnP11oJWgjkLO9OJt0 D8W2jHjvNyWiHTg19m1mfFDtFMtc8ZaejMGr1PyMqKNIeddfSGEdJl0nfrEOHRJM/sX0 FD8A1SsTe+ee89uTVXjmYAtZojWn+LQMZQQNmT6PZUqfv2hEAbUm2quEHFNhBo2Tvq51 mXUU/HA7D5McOFz2QyuunlSvH/cONbQ7MHhby6gGgBGbqnH4C8xBDDU/l1meaz7HMgWy 8x6g== X-Gm-Message-State: AOJu0Yz7xSmB3ZvWk2NFaEAdJ02JpqckH2ctA4cutWclP5LC5b0U81KD vp4oCtSeFHNqjwuA2eGQGlE= X-Google-Smtp-Source: AGHT+IGbhJJgcRO7Al1j9Lh8J9XP+Tac9kCgzi0rM8m7eBBfpIMCgeyQD/JVdVjpxfvf0xnEldYi3Q== X-Received: by 2002:a17:902:c711:b0:1c3:e2eb:f79d with SMTP id p17-20020a170902c71100b001c3e2ebf79dmr10770547plp.8.1697490973207; Mon, 16 Oct 2023 14:16:13 -0700 (PDT) Received: from [192.168.51.14] (c-73-231-117-72.hsd1.ca.comcast.net. [73.231.117.72]) by smtp.gmail.com with ESMTPSA id bb11-20020a170902bc8b00b001c5d09e9437sm76976plb.25.2023.10.16.14.16.11 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 16 Oct 2023 14:16:12 -0700 (PDT) Message-ID: Date: Mon, 16 Oct 2023 14:16:09 -0700 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH V2] Consider inflight IO in io accounting for high latency devices Content-Language: en-US To: Gulam Mohamed , "axboe@kernel.dk" , "linux-block@vger.kernel.org" , "linux-kernel@vger.kernel.org" References: <20231013195559.1306345-1-gulam.mohamed@oracle.com> <35e3e173-8018-42d8-a6e8-7ba994ff6b17@acm.org> From: Bart Van Assche In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/16/23 13:01, Gulam Mohamed wrote: > [GULAM]: Yes, it will be called for every submitted bio but for the > high latency devices it will not have much impact. This is indicated > by the latency figures I provided in the review mail, with and > without our patch. Calling tag iteration code from the hot path is wrong. There are more devices than only hard disks that have a single hardware queue, e.g. certain SSDs. I'm pretty sure that this patch will have a significant negative performance impact for such devices. Thanks, Bart.