From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-io1-f51.google.com (mail-io1-f51.google.com [209.85.166.51]) (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 890CA5FEEB for ; Fri, 12 Jan 2024 16:10:46 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=kernel.dk Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=kernel.dk Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel-dk.20230601.gappssmtp.com header.i=@kernel-dk.20230601.gappssmtp.com header.b="XPZGz+ja" Received: by mail-io1-f51.google.com with SMTP id ca18e2360f4ac-7bb5be6742fso78066539f.1 for ; Fri, 12 Jan 2024 08:10:46 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.20230601.gappssmtp.com; s=20230601; t=1705075845; x=1705680645; darn=vger.kernel.org; h=content-transfer-encoding:in-reply-to:from:references:cc:to :content-language:subject:user-agent:mime-version:date:message-id :from:to:cc:subject:date:message-id:reply-to; bh=NFWfwHygc2tLtqaZ9kmrB7jXlZ0tclJm6WoKHkdH7fk=; b=XPZGz+jaZFS4t2ooJLCdCoQd5eh1V0fJ5CUlVcq1sPAlhk8/gLMs6LY+TmI2a7For2 bLtDH23MmSRuzgjFKhKOcWo8DG119j3h+iJjS+u3UFF0fEUvr6BINhUs5vRflBcRjTHF 3xvVm2d+QzMc1hLWkf8dQRG4deMtNWpKFVkaHR6XolUiqxrlZ2jSdCJ/HgnDZ7iw83A/ MKyXzSX2Ebk5zBXd8ZdO/PhtO1mBbaODd94sSe+ns6zQV3e3cRMZrwes3STg6a/AtkL8 bd18x6ZAjWaIfzhfRYu9FdRb7lK2BEqI3y4+TruuEmBbNfxGpggvthh+IlE3aRtWvjA4 b/vg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1705075845; x=1705680645; h=content-transfer-encoding:in-reply-to:from:references:cc: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=NFWfwHygc2tLtqaZ9kmrB7jXlZ0tclJm6WoKHkdH7fk=; b=CeKlZeN3vYFqANuvD9pllFkvbs7XsN73c1eaSKaFn3NF/80Z1PQOjc4Ef4BNCUps0T V8hW7llXVJHcLcteaJLtD5kvQNDX7ozTYGJWALHsR0W1OYCmtQhsI6RL5Rw92yCcdph7 hn8sNhs0GvUxtisMkM1oUmJrYWJPpBrssaM6eAvcphQHiUzJ+YYDl/vIZAHIgT+exwCi Ck0jOxxnBcbQ/b5/QJTCNWj8e8x6sLJ1BW9cpzynfLIcwzbBVMit7fBCYXHe7Upn6ymP oX6ECSHDE9Sxqo8XFWU0UMSTSvHHJeCPrB2I/ZRM+/rq6nqeKb7Qoqm3dYhk+A6Fw0Cy jLSg== X-Gm-Message-State: AOJu0YwhepFh5VQs/j0pjdQXmMLZZD6VJpen+Vo7C4DmJkOfseO+XtjQ e3f62dpLx59jZmN+Dwxuv5TDxWHLoPNq9Q== X-Google-Smtp-Source: AGHT+IE5HSi9IwRSj+Eoiwy+OtCZgGENx3FKGiQyFSFBSLtYiehianEJtjDF35mgK6CVa1fFWXukmA== X-Received: by 2002:a05:6602:2558:b0:7be:f413:e410 with SMTP id cg24-20020a056602255800b007bef413e410mr2103714iob.2.1705075845625; Fri, 12 Jan 2024 08:10:45 -0800 (PST) Received: from [192.168.1.116] ([96.43.243.2]) by smtp.gmail.com with ESMTPSA id dn15-20020a056638090f00b0046e300e90d5sm937976jab.152.2024.01.12.08.10.44 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 12 Jan 2024 08:10:44 -0800 (PST) Message-ID: Date: Fri, 12 Jan 2024 09:10:44 -0700 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] blk-mq: ensure a q_usage_counter reference is held when splitting bios Content-Language: en-US To: Christoph Hellwig Cc: Ming Lei , linux-block@vger.kernel.org, Ulf Hansson , linux-mmc@vger.kernel.org References: <20240112054449.GA6829@lst.de> <9eb0f18e-f3ce-497c-931d-339efee2190d@kernel.dk> <20240112142509.GA6899@lst.de> From: Jens Axboe In-Reply-To: <20240112142509.GA6899@lst.de> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 1/12/24 7:25 AM, Christoph Hellwig wrote: > On Fri, Jan 12, 2024 at 07:22:18AM -0700, Jens Axboe wrote: >> Yep it is pretty cheap, but it's not free. Here's a test where we just >> grab a ref and drop it, which should arguably be cheaper than doing a >> ref at the top and dropping it at the bottom due to temporal locality: >> >> 5.01% +0.86% [kernel.vmlinux] [k] blk_mq_submit_bio > > Ok. Do you want to send out your version formally? Sure, can do. I'll pick your first patch here as that one makes sense separately. -- Jens Axboe