From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pl1-f172.google.com (mail-pl1-f172.google.com [209.85.214.172]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2986B2E3F0 for ; Thu, 18 Jan 2024 18:53:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1705603983; cv=none; b=r9Z1Ee19I0vMClfxszF3kosBDSRsRUyxNIVFGTcUvpte6KgV5JsH6LRx9Q3azEDMgk1QQF0RCGPUEPXKIcTN99Gaj/KyZjxKlt77HI1T3ocGjKoCVxxyUHi6R3jEoPImg6oP72PvWVBYfLJcZ2nWQxuJyou3xoya7UVs4zqiiys= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1705603983; c=relaxed/simple; bh=yOuMewM5I56TmsFTuQuUBwa3Ko3nUD86QcAOcV6ayj0=; h=Message-ID:Date:MIME-Version:Subject:To:References:From: In-Reply-To:Content-Type; b=L4IVlPUUUqCOvts7CkEV2P/Cg/HecTBe/A+QTXaUkk2sy5RFoGIrsWw+CNfJcdq78l8BDprQHbF9E0nbpPiU3k+gcnSWW35WWEmLp4uMC8MbWX6BwMN7ru36GGdPcC3qhCtCnz9mIb0KvsVPRlReJqsZkm3qMZ5O8qkVTxtyB7Q= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=acm.org; spf=pass smtp.mailfrom=gmail.com; arc=none smtp.client-ip=209.85.214.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=acm.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Received: by mail-pl1-f172.google.com with SMTP id d9443c01a7336-1d427518d52so227745ad.0 for ; Thu, 18 Jan 2024 10:53:01 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1705603981; x=1706208781; 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=xQ0Tr5vMRHBDr8II3iK9yvuEASEw+zRgGpxjO0mTQ38=; b=Q0zd0zuLeN4u2NWqv3zHqYBIn7XPb99JlHlugwfyPmkB7uCSIbs5RmMiLGvL2zyxzH 2xbyK7OtgXjQe4HPdlyFABfcpF6DA3Ud58KfFnjdmAZJfejioCntL2Wo5o6kM6t5pwpq DiZFvfrY8OIhd0gn70bmw70smpuLRHQRPGIzBLQGvdsYirnxuQnGkgMnexHw6WuthO19 8VYzsqTjMSCAymnEIXakJ1fBXieG/FUoO7o3WnYfVg1ahy+KDw4Lnbh/cpd3mx30eU5c aDn6OAbBRyD8Hl0H8E5+PHjFpX95OcFvBQ+PKrbl2ps89O00iD1e5dycDDPd2CM/TJ2n cRGw== X-Gm-Message-State: AOJu0YxXSnrwRWyQxsE0MXWz1iV9r9WjMUyOFAlRbEsopou4VgYqg4uj JoVFoi5Ev9CugAwi+MWs7oQuJ46l+5+NE5mfcgiz/rpsHYQXzULo X-Google-Smtp-Source: AGHT+IGUhnF8Y0Ph8I4CGB5Qj9etTWNocr3effEzE20zAHIVfGA9l9Lr1h6RFscQoQtcVJjx/sSZ8g== X-Received: by 2002:a17:902:e5d1:b0:1d5:e75a:6900 with SMTP id u17-20020a170902e5d100b001d5e75a6900mr2192559plf.39.1705603981290; Thu, 18 Jan 2024 10:53:01 -0800 (PST) Received: from ?IPV6:2620:0:1000:8411:718b:ab80:1dc2:cbee? ([2620:0:1000:8411:718b:ab80:1dc2:cbee]) by smtp.gmail.com with ESMTPSA id mf12-20020a170902fc8c00b001d39af62b1fsm1704172plb.232.2024.01.18.10.53.00 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 18 Jan 2024 10:53:00 -0800 (PST) Message-ID: Date: Thu, 18 Jan 2024 10:53:00 -0800 Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 2/2] block/mq-deadline: fallback to per-cpu insertion buckets under contention Content-Language: en-US To: Jens Axboe , linux-block@vger.kernel.org References: <20240118180541.930783-1-axboe@kernel.dk> <20240118180541.930783-3-axboe@kernel.dk> <0ca63d05-fc5b-4e6a-a828-52eb24305545@acm.org> From: Bart Van Assche In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 1/18/24 10:33, Jens Axboe wrote: > On 1/18/24 11:31 AM, Bart Van Assche wrote: >> On 1/18/24 10:04, Jens Axboe wrote: >>> If we attempt to insert a list of requests but someone else is already >>> running an insertion, then fallback to queueing it internally and let >>> the existing inserter finish the operation. >> >> Because this patch adds significant complexity: what are the use cases >> that benefit from this kind of optimization? Are these perhaps workloads >> on systems with many CPU cores and fast storage? If the storage is fast, >> why to use mq-deadline instead of "none" as I/O-scheduler? > > You and others complain that mq-deadline is slow and doesn't scale, > these two patches help improve that situation. Not sure why this is even > a question? How much does this patch improve performance? Thanks, Bart.