From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from 011.lax.mailroute.net (011.lax.mailroute.net [199.89.1.14]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 22877313550; Tue, 5 May 2026 15:42:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=199.89.1.14 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777995737; cv=none; b=qiZZ1lHn4VHyBYZcJTYzTt/cjA0ra9TMkBNOk3BkH088RYkUExC/DsDJ1iiRSFKd6gTjIAV4YPZrTit9sJqX0y9s2KTvLOh48waw8KqiZAvJ7f/Y8B1R5xHr+IXt9NiVz7zeUyVhNzt4zq3Bjj7ftT26LgmurI/1eW7B3JCiI5c= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777995737; c=relaxed/simple; bh=BzcEHEyglD+WwAtGnnN4RinbaNx/5QoNqm9JCn3CYno=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=EHDOEJVuDiHoBTq4eL9q235kmj/GRilT1s9e+K9XgDG+kOD85wpqMkpeRT9+kL7/3blcx7/2ECymGOhuDytw5BaWNEzgAc76ZmLQd5yUoN/ph50ACKfknIYhfOIJwbIhRpKHXJ8oQ8y220Ex1xLt7rVpFpJ92aq9QvstSeP8IFA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=acm.org; spf=pass smtp.mailfrom=acm.org; dkim=pass (2048-bit key) header.d=acm.org header.i=@acm.org header.b=vwVl88ik; arc=none smtp.client-ip=199.89.1.14 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=acm.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=acm.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=acm.org header.i=@acm.org header.b="vwVl88ik" Received: from localhost (localhost [127.0.0.1]) by 011.lax.mailroute.net (Postfix) with ESMTP id 4g92ng3wkkz1XM6JP; Tue, 5 May 2026 15:42:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=acm.org; h= content-transfer-encoding:content-type:content-type:in-reply-to :from:from:content-language:references:subject:subject :user-agent:mime-version:date:date:message-id:received:received; s=mr01; t=1777995728; x=1780587729; bh=q1qNYl6x7rCJ4Lu/FnvPoVV1 JRQuZdv0mQEcO93DffE=; b=vwVl88ik6UpR9sfpl1/c13zyBCBGhV8CY1Qgh7Gu y6af7E02G90xWkV5OOuNILuDXUrRP7mKyKf9u4Lp5efJs4vtsqPTm/u406JSZYM6 4XVVK+6n0BbHYEsyh/fyKWiaEjcyB3lQsMxKEwue4+NKKm+HPp1zY/kozAY6iuMn 8iBw54sX5qH26mHFiLNBBNbB2NA3g5HQCEV9dxfzw1M1s2eh8Mn9D1O33O40OPgt axxIhHWapQxweSDFnaQLROIoDO58YZ4UdxaTZt86CcvzIsTcH9ep94NSc09p+vcP PsGtoIGxCXnSBXFFP0KDoGNSn3y/O+6JDEnSIrODi4G84A== X-Virus-Scanned: by MailRoute Received: from 011.lax.mailroute.net ([127.0.0.1]) by localhost (011.lax [127.0.0.1]) (mroute_mailscanner, port 10029) with LMTP id EX2hhIESClJK; Tue, 5 May 2026 15:42:08 +0000 (UTC) Received: from [10.211.9.52] (unknown [213.147.98.98]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: bvanassche@acm.org) by 011.lax.mailroute.net (Postfix) with ESMTPSA id 4g92nM4f6Jz1XM5kD; Tue, 5 May 2026 15:41:58 +0000 (UTC) Message-ID: <7c811a44-6d7e-499c-8203-90a256984912@acm.org> Date: Tue, 5 May 2026 17:41:55 +0200 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 v5 1/1] block/blk-mq: use atomic_t for quiesce_depth to avoid lock contention on RT To: "Ionut Nechita (Wind River)" , linux-block@vger.kernel.org, axboe@kernel.dk Cc: bigeasy@linutronix.de, clrkwllms@kernel.org, rostedt@goodmis.org, ming.lei@redhat.com, muchun.song@linux.dev, mkhalfella@purestorage.com, chris.friesen@windriver.com, linux-kernel@vger.kernel.org, linux-rt-devel@lists.linux.dev, linux-rt-users@vger.kernel.org, stable@vger.kernel.org, ionut_n2001@yahoo.com, sunlightlinux@gmail.com References: <20260303073744.20585-1-ionut.nechita@windriver.com> <20260303073744.20585-2-ionut.nechita@windriver.com> Content-Language: en-US From: Bart Van Assche In-Reply-To: <20260303073744.20585-2-ionut.nechita@windriver.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 3/3/26 8:37 AM, Ionut Nechita (Wind River) wrote: > + /* > + * Ensure the store to quiesce_depth is visible before any > + * subsequent loads in blk_mq_run_hw_queue(). > + */ This comment does not make sense to me. How could there be a dependency of blk_mq_run_hw_queue() on *loads* that happen in blk_mq_quiesce_queue_nowait() after atomic_inc(&q->quiesce_depth)? Bart.