From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 B05B2319155; Fri, 5 Sep 2025 15:00:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757084425; cv=none; b=KpJA0uMeEYWz9be47KkLgb5AEHmMeefNbJL2xtD3zt02WqzfjLQaxP6mKBH7dTvGPLXfVBFl6MO7ScLH/rwU0UgLgyrTQkUV9yy4mmVi4hTmi42UG4zifLkHTIIGJiAmNHsxqSP7DXhuo1kux+v5bGsAYQYRaH90fGuwx5FQgTA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757084425; c=relaxed/simple; bh=RKC5z2WEU+s9nBjTQYx3DaugYt9DytA+/DWNBaUypdE=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=syGgdnUuO8pwpSOG5rY9Ob8Zsav4ujUFINW+0A7ZfVpDkZ+BUqAO/ILoo/voGwFmRI2duNYG9n3J0gZfk5X7iPkxYvXQ2BZMnwKTaNSLXrIE0FtK+CAtX/AtcUjRars47/BoW8M6Vjv21m6VweLeQyIcjpm+i9wSX9ehhFAdx6s= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=sdOJ0F9e; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="sdOJ0F9e" Received: by smtp.kernel.org (Postfix) with ESMTPSA id BE966C4CEF1; Fri, 5 Sep 2025 15:00:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1757084425; bh=RKC5z2WEU+s9nBjTQYx3DaugYt9DytA+/DWNBaUypdE=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=sdOJ0F9ep89rr4t3o8/YdBRPJXANT7KvK1l6wVoWK5hT+7RrAFPu7P7yvCtLjUNin UWU0IvjEbPVaIumQNVPqpiDWuo0KBRoY3YYnnRwVG9N8Y06YbZa3BGM0CP0De/3BUC zeOPR9WTjFPrPSbX6Agci88zzzpLwsYF46vjbws4T/MRpFe5Tmyo2tIqzn5B+zNASZ fFWG+qUuyG2llvuPe8xW5H1Xd4yi96YOQWCFcQzYs68Pj74mTXs3je77nc1Biqn2eP AoOxHFbFfKvsUi3YYjC0ajgB6+6yh/9fDqIGJFNMvxS/7NQXCUgp5kDECQr18le+kQ LNiKjOHLdfbeg== From: Daniel Wagner Date: Fri, 05 Sep 2025 16:59:58 +0200 Subject: [PATCH v8 12/12] docs: add io_queue flag to isolcpus Precedence: bulk X-Mailing-List: virtualization@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20250905-isolcpus-io-queues-v8-12-885984c5daca@kernel.org> References: <20250905-isolcpus-io-queues-v8-0-885984c5daca@kernel.org> In-Reply-To: <20250905-isolcpus-io-queues-v8-0-885984c5daca@kernel.org> To: Jens Axboe , Keith Busch , Christoph Hellwig , Sagi Grimberg , "Michael S. Tsirkin" Cc: Aaron Tomlin , "Martin K. Petersen" , Thomas Gleixner , Costa Shulyupin , Juri Lelli , Valentin Schneider , Waiman Long , Ming Lei , Frederic Weisbecker , Mel Gorman , Hannes Reinecke , Mathieu Desnoyers , Aaron Tomlin , linux-kernel@vger.kernel.org, linux-block@vger.kernel.org, linux-nvme@lists.infradead.org, megaraidlinux.pdl@broadcom.com, linux-scsi@vger.kernel.org, storagedev@microchip.com, virtualization@lists.linux.dev, GR-QLogic-Storage-Upstream@marvell.com, Daniel Wagner X-Mailer: b4 0.14.2 The io_queue flag informs multiqueue device drivers where to place hardware queues. Document this new flag in the isolcpus command-line argument description. Reviewed-by: Aaron Tomlin Reviewed-by: Hannes Reinecke Signed-off-by: Daniel Wagner --- Documentation/admin-guide/kernel-parameters.txt | 22 +++++++++++++++++++++- 1 file changed, 21 insertions(+), 1 deletion(-) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 747a55abf4946bb9efe320f0f62fdcd1560b0a71..4161d4277a7086f2a3726617826c50888eefb260 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -2653,7 +2653,6 @@ "number of CPUs in system - 1". managed_irq - Isolate from being targeted by managed interrupts which have an interrupt mask containing isolated CPUs. The affinity of managed interrupts is @@ -2676,6 +2675,27 @@ housekeeping CPUs has no influence on those queues. + io_queue + Isolate from I/O queue work caused by multiqueue + device drivers. Restrict the placement of + queues to housekeeping CPUs only, ensuring that + all I/O work is processed by a housekeeping CPU. + + The io_queue configuration takes precedence + over managed_irq. When io_queue is used, + managed_irq placement constrains have no + effect. + + Note: Offlining housekeeping CPUS which serve + isolated CPUs will be rejected. Isolated CPUs + need to be offlined before offlining the + housekeeping CPUs. + + Note: When an isolated CPU issues an I/O request, + it is forwarded to a housekeeping CPU. This will + trigger a software interrupt on the completion + path. + The format of is described above. iucv= [HW,NET] -- 2.51.0