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Mon, 13 Oct 2025 01:26:21 -0700 (PDT) X-Google-Smtp-Source: AGHT+IEqxQ3r8mKG19gkUS7w6zdeOC2dbsppCKLD7LIyf0aaxI4o4mEw27yhWt4MDd3wyBHEFiKHvB7PUDNAXpEj720= X-Received: by 2002:a05:6102:8399:10b0:5d6:bbe:fe00 with SMTP id ada2fe7eead31-5d60bbf01ccmr1298632137.10.1760343981594; Mon, 13 Oct 2025 01:26:21 -0700 (PDT) Precedence: bulk X-Mailing-List: io-uring@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 References: <20250928132927.3672537-1-ming.lei@redhat.com> <20250928132927.3672537-7-ming.lei@redhat.com> In-Reply-To: From: Ming Lei Date: Mon, 13 Oct 2025 16:26:08 +0800 X-Gm-Features: AS18NWCWxgbBN23g61iYzMfQYeFdjbQ0IHgI_c-2448u3QBnJ6IKRiHfJ5F8vfs Message-ID: Subject: Re: [PATCH V4 6/6] loop: add hint for handling aio via IOCB_NOWAIT To: Christoph Hellwig Cc: Jens Axboe , linux-block@vger.kernel.org, Mikulas Patocka , Zhaoyang Huang , Dave Chinner , linux-fsdevel@vger.kernel.org, io-uring@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Mon, Oct 13, 2025 at 2:28=E2=80=AFPM Christoph Hellwig wrote: > > On Thu, Oct 09, 2025 at 09:25:47AM +0800, Ming Lei wrote: > > Firstly this FS flag isn't available, if it is added, we may take it in= to > > account, and it is just one check, which shouldn't be blocker for this > > loop perf improvement. > > > > Secondly it isn't enough to replace nowait decision from user side, one > > case is overwrite, which is a nice usecase for nowait. > > Yes. But right now you are hardcoding heuristics which is overall a > very minor user of RWF_NOWAIT instead of sorting this out properly. Yes, that is why I call the hint as loop specific, it isn't perfect, just f= or avoiding potential regression by taking nowait. Given the improvement is big, and the perf issue has been reported several times, I'd suggest taking it this way first, and document it can be improved in future. Thanks,