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Fri, 16 Oct 2026 09:15:20 -0400 (EDT) Message-ID: Date: Fri, 16 Oct 2026 15:15:19 +0200 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: [RFC PATCH 0/1] fuse: per-queue background request accounting for io-uring To: Aleksander Trofimowicz , fuse-devel@lists.linux.dev, linux-kernel@vger.kernel.org References: <20261016124820.316741-1-trof@n90.eu> From: Bernd Schubert Content-Language: fr, en-US, de-DE, ru-RU In-Reply-To: <20261016124820.316741-1-trof@n90.eu> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Hi Alexsander, On 10/16/26 14:48, Aleksander Trofimowicz wrote: > fuse: per-queue background request accounting for io-uring > > This RFC proposes an opt-in path to replace the connection-wide > background request accounting in fuse io-uring with per-queue > budgeting. > > AFAIR the concept has already floated on the list, but nothing has > come to fruition. Nonetheless the problem is obvious: the existing > implementation relies on a single connection-wide spinlock > (fch->bg_lock) that is taken twice while servicing background > requests. That severely hampers the scalability of fuse io-uring for > certain types of workload (e.g. direct async I/O). Suffice it to say, > with this patch applied I can easily cross the 1M 4k random read IOPS > barrier, while the baseline gives a mere 600k IOPS (caeteris paribus). > > I envision this enhancement being negotiated with a daemon, but for > your convenience the feature can currently be activated > unconditionally via the uring_max_bg_per_queue_force parameter. Mind > that the value of uring_max_bg_per_queue must also be increased to > obtain any meaningful results. > > I am looking forward to your feedback. Thanks in advance. I wasn't doing this yet, because I see it dependent on the reduced queue feature, which also allows to distribute requests to another queue, when a queue already got too many requests. I.e. if a queue is over its own bg-limit, it should check if other queues are available. I plan to send out next version of reduced queues over the weekend. Thanks, Bernd