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 B4F9BC433F5 for ; Mon, 25 Apr 2022 03:09:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240542AbiDYDMI (ORCPT ); Sun, 24 Apr 2022 23:12:08 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41776 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240474AbiDYDMH (ORCPT ); Sun, 24 Apr 2022 23:12:07 -0400 Received: from mail-pf1-f172.google.com (mail-pf1-f172.google.com [209.85.210.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8B4C64E385; Sun, 24 Apr 2022 20:09:04 -0700 (PDT) Received: by mail-pf1-f172.google.com with SMTP id i24so13579084pfa.7; Sun, 24 Apr 2022 20:09:04 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:message-id:date:mime-version:user-agent:subject :content-language:to:cc:references:from:in-reply-to :content-transfer-encoding; bh=tsGZFIEixUEnJNolXV8dfGKJqfTCfEpZ3B2cSrfx1vM=; b=eWbthMyR5pl1rFlPdMKr3HSLFSx73sk+wZ1uL96OKuPPahT/UJrpXsIkRtJRNAuCPN SZxKyWI70mcH+164+Um+v1onym4X4h+w11oNv0UkFLZvD10Gc/gidP138PHMOlE066iA Qs7Y2SWaimJBdX2sa6G7tZ6NDzzEv810ic0NC/KxYmZlphJ1ijHTLT7Q5ZmbEcRbC48f Pa6aBeDNFJ5hOpXcOqG0QDLUSTtDap6VAnSEWgf7/j04nJMpqcK5LSUuP3PJAGBcKSzY XugPnCCRPHSpHKZ0GLup7sgjpM5+1PY5L5d7S1PWxgMsaN0vyo8w9XBCu728UsefeJ8b qbeg== X-Gm-Message-State: AOAM532k9noiUdzKMgIkVI2hTf86GQdehfXvov2VyY5HY/AKD7f39DBX OqdSuLVZnlO2DxeAuuEyusgRhrcCfyc= X-Google-Smtp-Source: ABdhPJzOQj9ikbTemWkl0X4L6g7+gJVC6zzs6svuR4Q/oiKun077BKe3V8PtBTFA63SVbSHmMXRfuw== X-Received: by 2002:a05:6a00:2d0:b0:4f4:1f34:e39d with SMTP id b16-20020a056a0002d000b004f41f34e39dmr16617024pft.14.1650856143804; Sun, 24 Apr 2022 20:09:03 -0700 (PDT) Received: from ?IPV6:2601:647:4000:d7:feaa:14ff:fe9d:6dbd? ([2601:647:4000:d7:feaa:14ff:fe9d:6dbd]) by smtp.gmail.com with ESMTPSA id t2-20020a17090a448200b001cd4989ff40sm9147432pjg.7.2022.04.24.20.09.02 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 24 Apr 2022 20:09:02 -0700 (PDT) Message-ID: <450b5ab6-fb82-06dc-2a11-e0b464901c74@acm.org> Date: Sun, 24 Apr 2022 20:09:01 -0700 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.7.0 Subject: Re: [PATCH -next RFC v3 0/8] improve tag allocation under heavy load Content-Language: en-US To: Yu Kuai , axboe@kernel.dk, andriy.shevchenko@linux.intel.com, john.garry@huawei.com, ming.lei@redhat.com, qiulaibin@huawei.com Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, yi.zhang@huawei.com References: <20220415101053.554495-1-yukuai3@huawei.com> From: Bart Van Assche In-Reply-To: <20220415101053.554495-1-yukuai3@huawei.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On 4/15/22 03:10, Yu Kuai wrote: > The single io performance(randwrite): > > | bs | 128k | 256k | 512k | 1m | 1280k | 2m | 4m | > | -------- | ---- | ---- | ---- | ---- | ----- | ---- | ---- | > | bw MiB/s | 20.1 | 33.4 | 51.8 | 67.1 | 74.7 | 82.9 | 82.9 | Although the above data is interesting, it is not sufficient. The above data comes from a setup with a single hard disk. There are many other configurations that are relevant (hard disk array, high speed NVMe, QD=1 USB stick, ...) but for which no conclusions can be drawn from the above data. Another question is whether the approach of this patch series is the right approach? I would expect that round-robin wakeup of waiters would be ideal from a fairness point of view. However, there are patches in this patch series that guarantee that wakeup of tag waiters won't happen in a round robin fashion. Thanks, Bart.