From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on gnuweeb.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=5.0 tests=ALL_TRUSTED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,NO_DNS_FOR_FROM autolearn=no autolearn_force=no version=3.4.6 Received: from localhost.localdomain (unknown [182.253.183.169]) by gnuweeb.org (Postfix) with ESMTPSA id 8E101831BF; Sun, 26 Feb 2023 16:26:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gnuweeb.org; s=default; t=1677428813; bh=9m8PE6sXBOFOOOY6NkqZStqOnmlRwk8q43mx8hniEY4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=JT9v5qKVM1voQrmRYpgWpLLalX8AeNQ2wWeaC2DNNLGWvaUNKhhMMFVQ674uPkpdb QLxrSwjGffkMgo5c36Exrfh/Z830WWlowPdJuf9+Yng2BuKCCCFf9bBWYd6w7EA0YS hA2Je+hJ+pW9BK8lQF2EZ1q5OPsWksOk3q/RAPE+R8nLETUfIH6yMEV+dDK3uESyl5 UZHMquwNIddXIzprSg+SAXzufhx0uC2QoSoQnM0Q2bDYm12o9vcwMxLN0FewZh8vg8 5DddegOIKAhARFBYd4pTuuSv/JwelVf4IUb4iGsYrKLfdl/fMXB/viK8PEEPGnmOAs lACT6/6osOMQQ== From: Ammar Faizi To: Chris Mason , Josef Bacik , David Sterba Cc: Ammar Faizi , Filipe Manana , Linux Doc Mailing List , Linux Btrfs Mailing List , Linux Kernel Mailing List , Linux Fsdevel Mailing List , GNU/Weeb Mailing List Subject: [RFC PATCH v1 1/2] Documentation: btrfs: Document wq_cpu_set mount option Date: Sun, 26 Feb 2023 23:26:38 +0700 Message-Id: <20230226162639.20559-2-ammarfaizi2@gnuweeb.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230226162639.20559-1-ammarfaizi2@gnuweeb.org> References: <20230226162639.20559-1-ammarfaizi2@gnuweeb.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit List-Id: Document a new Btrfs mount option, wq_cpu_set. Signed-off-by: Ammar Faizi --- Documentation/ch-mount-options.rst | 29 +++++++++++++++++++++++++++++ 1 file changed, 29 insertions(+) diff --git a/Documentation/ch-mount-options.rst b/Documentation/ch-mount-options.rst index f0f205dc20fa15ff..48fe63ee5e95c297 100644 --- a/Documentation/ch-mount-options.rst +++ b/Documentation/ch-mount-options.rst @@ -451,6 +451,35 @@ user_subvol_rm_allowed ordinary directory. Whether this is possible can be detected at runtime, see *rmdir_subvol* feature in *FILESYSTEM FEATURES*. +wq_cpu_set= + (since: 6.5, default: all online CPUs) + + Btrfs workqueues can slow sensitive user tasks down because they can use any + online CPU to perform heavy workloads on an SMP system. This option is used to + isolate the Btrfs workqueues to a set of CPUs. It is helpful to avoid + sensitive user tasks being preempted by Btrfs heavy workqueues. + + The *cpu_set* is a dot-separated list of decimal numbers and ranges. The + numbers are CPU numbers, the ranges are inclusive. For example: + + - *wq_cpu_set=0.3-7* will use CPUs 0, 3, 4, 5, 6 and 7. + + - *wq_cpu_set=0.4.1.5* will use CPUs 0, 1, 4 and 5. + + This option is similar to the taskset bitmask except that the comma separator + is replaced with a dot. The reason for this is that the mount option parser + uses commas to separate mount options. + + If *wq_cpu_set* option is specificed and the *thread_pool* option is not, the + number of default max thread pool size will be set to the number of online + CPUs in the specified CPU set plus 2, if and only if the resulting number is + less than 8. + + If *wq_cpu_set* option is specificed and the *thread_pool* option is also + specified, the thread pool size will be set to the value of *thread_pool* + option. + + DEPRECATED MOUNT OPTIONS ^^^^^^^^^^^^^^^^^^^^^^^^ -- Ammar Faizi