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Thu, 09 Apr 2026 11:54:28 -0700 (PDT) X-Received: by 2002:a0c:f114:0:b0:8a3:221d:9095 with SMTP id 6a1803df08f44-8ac743038b7mr72760866d6.15.1775760868507; Thu, 09 Apr 2026 11:54:28 -0700 (PDT) Received: from [10.206.71.59] ([129.236.231.31]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-8ac849db4b8sm3093516d6.7.2026.04.09.11.54.27 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 09 Apr 2026 11:54:27 -0700 (PDT) Message-ID: <7e468bd2-e52b-4165-95c6-3f04e1dca21e@columbia.edu> Date: Thu, 9 Apr 2026 14:54:27 -0400 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH RFC v4 1/3] block: add BIO_COMPLETE_IN_TASK for task-context completion To: Jens Axboe Cc: Matthew Wilcox , Christian Brauner , "Darrick J. Wong" , Carlos Maiolino , Alexander Viro , Jan Kara , Christoph Hellwig , linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org References: <97b81868-6410-4c79-a242-679a9f04f073@columbia.edu> <95F28FA1-5CEF-4E80-BBB7-A429B4437D12@kernel.dk> Content-Language: en-US From: Tal Zussman In-Reply-To: <95F28FA1-5CEF-4E80-BBB7-A429B4437D12@kernel.dk> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNDA5MDE3MyBTYWx0ZWRfX4RJuij7O53zi Na77GchE1zweqG2TIVPHfXvOrRrKcGyMgC2CDFzEmuq8cG3ENbaWmFJ01847ascrJrDFx2nbU21 5AFJmzdyK65EYnq46H+ZRqPKJeRVOs93U1jNqkM8lK0Nvp113LWvcQkiX9PSBW5v81jRVvlNuuR UGiHjwnS5KEnzOFvrARVogi/M6QiOgZYcyTSIBZBFOXwPdGsEyhQgBir4LBlDnd0bpKq4Z7sJy4 +oY915lvbmcLn84MlUighvYbo+Ry1XtZH15zurCnNsH0+IE79fSLj0vw60TSjTkMCMfnrj2ROqk 5Vd0Qzd7BDq5PjDBIOcmBSR7ojwgFqW24lLzoKakJ0n28CyofGsWzKwtAmFs49jKLY+s+UgQ59I /ccVJxC6u3qWafi60t7aqOcCEw4n67AR+xd3znUdrxaZ0ylxhoXfbFjJMNyglzZrPpzrss/V/ND cdhnBTA0vsx1PexH+CQ== X-Proofpoint-ORIG-GUID: 7xVSEIM34yAVCipNNUJjxnLkpNZXvaOy X-Proofpoint-GUID: 7xVSEIM34yAVCipNNUJjxnLkpNZXvaOy X-Authority-Analysis: v=2.4 cv=UZthjqSN c=1 sm=1 tr=0 ts=69d7f5e5 cx=c_pps a=wEM5vcRIz55oU/E2lInRtA==:117 a=RFpAoTwO7tzpE9r8PTiuXw==:17 a=IkcTkHD0fZMA:10 a=A5OVakUREuEA:10 a=x7bEGLp0ZPQA:10 a=VkNPw1HP01LnGYTKEx00:22 a=Da8U98TiO7q1upZEImrf:22 a=jHxIr1HyPKZ_Q5_91PL3:22 a=y2ETOFklOQM5vU7YwEUA:9 a=3ZKOabzyN94A:10 a=QEXdDO2ut3YA:10 a=OIgjcC2v60KrkQgK7BGD:22 X-Proofpoint-Virus-Version: vendor=nai engine=6800 definitions=11754 signatures=596818 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 malwarescore=0 bulkscore=10 clxscore=1015 impostorscore=10 lowpriorityscore=10 phishscore=0 priorityscore=1501 spamscore=0 adultscore=0 suspectscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2604010000 definitions=main-2604090173 On 4/8/26 7:36 PM, Jens Axboe wrote: > On Apr 8, 2026, at 4:51 PM, Tal Zussman wrote: >>> On 4/8/26 3:51 PM, Jens Axboe wrote: >>>> On 4/8/26 12: 48 PM, Tal Zussman wrote: > On 3/25/26 4: 14 PM, Jens Axboe wrote: >>>> >>>> Thanks! I'm going to give Dave's llist suggestion a shot on top of >>>> this as it seems like it'll simplify this nicely. Looks like that'll >>>> involve turning bio::bi_next into a union with a struct llist_node. >>> >>> Since these lists can get long, I'd keep an eye on llist reversal >>> overhead there... >>> >> >> Going to send v5 shortly -- tested with and without the llist reversal and >> it didn't seem to make much of a difference. This was on a single-disk VM >> though, so any stress testing you could do would be very helpful. >> > > With all due respect, a single test like that isn’t going to be that useful. I’d be wary of making that change willy nilly and just thinking “it’s fine, worked fine on the one case I tested”. Understood -- unfortunately that's what I have access to at the moment. I can requisition a machine with 2, maybe 3 disks, and test more thoroughly on that before sending the next version, but that'll take a few days. You had previously offered to test on your big box, so was hoping that was still on the table :) (Although Christoph seems to have proposed moving away from llist again) > — > Jens Axboe >