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[142.68.26.201]) by smtp.gmail.com with ESMTPSA id c2-20020a05620a134200b00767c961eb47sm4446339qkl.43.2023.10.10.09.09.19 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 10 Oct 2023 09:09:19 -0700 (PDT) Received: from jgg by wakko with local (Exim 4.95) (envelope-from ) id 1qqFIN-000F7A-50; Tue, 10 Oct 2023 13:09:19 -0300 Date: Tue, 10 Oct 2023 13:09:19 -0300 From: Jason Gunthorpe To: "Daisuke Matsuda (Fujitsu)" Cc: 'Zhu Yanjun' , Bart Van Assche , Bob Pearson , Leon Romanovsky , "zyjzyj2000@gmail.com" , "linux-rdma@vger.kernel.org" , "shinichiro.kawasaki@wdc.com" , "linux-scsi@vger.kernel.org" , Zhu Yanjun Subject: Re: [PATCH 1/1] Revert "RDMA/rxe: Add workqueue support for rxe tasks" Message-ID: <20231010160919.GC55194@ziepe.ca> References: <2d5e02d7-cf84-4170-b1a3-a65316ac84ee@acm.org> <2fcef3c8-808e-8e6a-b23d-9f1b3f98c1f9@linux.dev> <552f2342-e800-43bc-b859-d73297ce940f@acm.org> <20231004183824.GQ13795@ziepe.ca> <20231005142148.GA970053@ziepe.ca> <6a730dad-9d81-46d9-8adc-764d00745b01@acm.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org On Tue, Oct 10, 2023 at 04:53:55AM +0000, Daisuke Matsuda (Fujitsu) wrote: > Solution 1: Reverting "RDMA/rxe: Add workqueue support for rxe tasks" > I see this is supported by Zhu, Bart and approved by Leon. > > Solution 2: Serializing execution of work items > > - rxe_wq = alloc_workqueue("rxe_wq", WQ_UNBOUND, WQ_MAX_ACTIVE); > > + rxe_wq = alloc_workqueue("rxe_wq", WQ_HIGHPRI | WQ_UNBOUND, 1); > > Solution 3: Merging requester and completer (not yet submitted/tested) > https://lore.kernel.org/all/93c8ad67-f008-4352-8887-099723c2f4ec@gmail.com/ > Not clear to me if we should call this a new feature or a fix. > If it can eliminate the hang issue, it could be an ultimate solution. > > It is understandable some people do not want to wait for solution 3 to be submitted and verified. > Is there any problem if we adopt solution 2? > If so, then I agree to going with solution 1. > If not, solution 2 is better to me. I also do not want to go backwards, I don't believe the locking is magically correct under tasklets. 2 is painful enough to continue to motivate people to fix this while unbreaking block tests. I'm still puzzled why Bob can't reproduce the things Bart has seen. Jason