From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from 008.lax.mailroute.net (008.lax.mailroute.net [199.89.1.11]) (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 2DC3A45BE4; Thu, 30 May 2024 17:11:29 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=199.89.1.11 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1717089091; cv=none; b=gUdfIh8OT6X+brsgPk2x0c3TdubG9/HbDpT8UpSDJvhh+ofIIw8GTFpnVPkBP8yoyu5kY392HVG9uiLaAlyIup/OWUDnXuu9/FUrNHIGsTqn8yKjadnllQnGn02CGYP16Df0CI3MzGuYtoPCZEMX1yoB3oku19byljw6zlYq0HU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1717089091; c=relaxed/simple; bh=go0cYzcDqydRtutKma5FUwv79zZ3P7zOWhGl/8O+3OI=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=CkVKFvLxaJsigiQ7RfCmp0CXKIatuPkMJ3ptN6HMGuXul6xUF3h6XZFT1jHUaR6QgZO1oJBnnDcvNGr2MwLexL2u2SSiL3EE1Wb4fjSoNtOt9UZ93vUqwPEym7NshI0Mupmx6sh1vEQm7l5bnukrFtMHSfyCSP2xsoPooxj65Dw= 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=pDdrsLN3; arc=none smtp.client-ip=199.89.1.11 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="pDdrsLN3" Received: from localhost (localhost [127.0.0.1]) by 008.lax.mailroute.net (Postfix) with ESMTP id 4Vqt812W1wz6Cnk9F; Thu, 30 May 2024 17:11:29 +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=1717089079; x=1719681080; bh=Ul8tShPV3DUMrLj4E7kNdLyB ZmST2o57Jd5aN0FDWYg=; b=pDdrsLN3JZPbFaUtLRbj37cnYuTv29wYsaoWbWPX 0jAfS4sWOekodOat3cJMbqn2RuFn9uq1dvv60rD84RsGZNOhy608uxLLU+fhbyly eKTbCc9wykATpOsmXQs1/utBwypcCkWl3KNU2MCRI5q96GhEKAOJtbitLN7/YNmG 3Mn9taXV/EfZN1zWvkxJYjfq7QJgcsxlE8NwOH4KI1q7OAQMt6CrARV53oLIJ5CE jigej7/3tFmHOi5xt9zZPOhIruRk26PiBfPzT3bdqB0Juw5GHorv14poLk5Hg7m/ 4sx7azLGVHPrQJdDegiabUIRkEKLqqQMji0NKTMLKSNjWA== X-Virus-Scanned: by MailRoute Received: from 008.lax.mailroute.net ([127.0.0.1]) by localhost (008.lax [127.0.0.1]) (mroute_mailscanner, port 10029) with LMTP id T0Ifl3ssZIoq; Thu, 30 May 2024 17:11:19 +0000 (UTC) Received: from [100.96.154.26] (unknown [104.132.0.90]) (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 008.lax.mailroute.net (Postfix) with ESMTPSA id 4Vqt7l6w1zz6Cnk97; Thu, 30 May 2024 17:11:15 +0000 (UTC) Message-ID: Date: Thu, 30 May 2024 10:11:15 -0700 Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v20 02/12] Add infrastructure for copy offload in block and request layer. To: Nitesh Shetty Cc: Damien Le Moal , Jens Axboe , Jonathan Corbet , Alasdair Kergon , Mike Snitzer , Mikulas Patocka , Keith Busch , Christoph Hellwig , Sagi Grimberg , Chaitanya Kulkarni , Alexander Viro , Christian Brauner , Jan Kara , martin.petersen@oracle.com, david@fromorbit.com, hare@suse.de, damien.lemoal@opensource.wdc.com, anuj20.g@samsung.com, joshi.k@samsung.com, nitheshshetty@gmail.com, gost.dev@samsung.com, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, dm-devel@lists.linux.dev, linux-nvme@lists.infradead.org, linux-fsdevel@vger.kernel.org References: <20240520102033.9361-1-nj.shetty@samsung.com> <20240520102033.9361-3-nj.shetty@samsung.com> <20240529061736.rubnzwkkavgsgmie@nj.shetty@samsung.com> <9f1ec1c1-e1b8-48ac-b7ff-8efb806a1bc8@kernel.org> <665850bd.050a0220.a5e6b.5b72SMTPIN_ADDED_BROKEN@mx.google.com> Content-Language: en-US From: Bart Van Assche In-Reply-To: <665850bd.050a0220.a5e6b.5b72SMTPIN_ADDED_BROKEN@mx.google.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: quoted-printable On 5/30/24 00:16, Nitesh Shetty wrote: > +static inline bool blk_copy_offload_attempt_combine(struct request_que= ue *q, > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 = struct bio *bio) > +{ > +=C2=A0=C2=A0=C2=A0 struct blk_plug *plug =3D current->plug; > +=C2=A0=C2=A0=C2=A0 struct request *rq; > + > +=C2=A0=C2=A0=C2=A0 if (!plug || rq_list_empty(plug->mq_list)) > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 return false; > + > +=C2=A0=C2=A0=C2=A0 rq_list_for_each(&plug->mq_list, rq) { > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 if (rq->q =3D=3D q) { > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 if = (!blk_copy_offload_combine(rq, bio)) > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0 return true; > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 bre= ak; > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 } > + > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 /* > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 * Only keep iterating= plug list for combines if we have multiple > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 * queues > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 */ > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 if (!plug->multiple_queues) > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 bre= ak; > +=C2=A0=C2=A0=C2=A0 } > +=C2=A0=C2=A0=C2=A0 return false; > +} This new approach has the following two disadvantages: * Without plug, REQ_OP_COPY_SRC and REQ_OP_COPY_DST are not combined. The= se two operation types are the only operation types for which not using a plu= g causes an I/O failure. * A loop is required to combine the REQ_OP_COPY_SRC and REQ_OP_COPY_DST o= perations. Please switch to the approach Hannes suggested, namely bio chaining. Chai= ning REQ_OP_COPY_SRC and REQ_OP_COPY_DST bios before these are submitted elimi= nates the two disadvantages mentioned above. Thanks, Bart.