From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6E624C433F5 for ; Thu, 13 Jan 2022 10:57:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233795AbiAMK5s (ORCPT ); Thu, 13 Jan 2022 05:57:48 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43742 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230368AbiAMK5p (ORCPT ); Thu, 13 Jan 2022 05:57:45 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B0695C06173F for ; Thu, 13 Jan 2022 02:57:45 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 4F65C61C50 for ; Thu, 13 Jan 2022 10:57:45 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3EC05C36AE3; Thu, 13 Jan 2022 10:57:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1642071464; bh=hWtQk270Tew4P7Iv97deTFrtkginL7C3gbx3tws3BDQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=LnNi9AFE7dPP/TR7FmAY2bcBnKz0kX8Jsa8bDM8on9PKjQcCXdP8nb1Nug5ra4G1V +uQNWGZljQPZiUBECYbXKC3oFwgwKnhRU+U1G1Z8ZBZxq4LJNRKNAcBd/JS6GGwb1A THTETJUeDEbrMqAHwTADW6CaVh0N6BZ84UpmsTdc= Date: Thu, 13 Jan 2022 11:57:41 +0100 From: Greg KH To: Imran Khan Cc: tj@kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3 0/2] kernfs: use hashed mutex and spinlock in place of global ones Message-ID: References: <20220113104259.1584491-1-imran.f.khan@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220113104259.1584491-1-imran.f.khan@oracle.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jan 13, 2022 at 09:42:57PM +1100, Imran Khan wrote: > Reduce contention around global locks used in kernfs. > > PATCH-1: Make global kernfs_open_file_mutex and kernfs_open_node_lock > hashed locks, where address of a kernfs_node acts as hash key. > This results in kernfs_node objects, whose address give the > different hash value, using different kernfs_open_file_mutex > and kernfs_open_node_lock rather than all kernfs_node objects > using the same kernfs_open_file_mutex and kernfs_open_node_lock > as was the case earlier. > > PATCH-2: Use a hashed rw_semaphore to access permissions, so that we can > avoid contention around global per-fs rw_semaphore, seen if > multiple applications are executing inode_permission and > walk_component in parallel when trying to open sysfs file(s). > > ------------------------------------------------------------------ > > Changes since v2: > - Remove RFC tag > - Use hashed locks rather than using per kernfs_node specific lock > (Suggested by Tejun Heo ) > I will look at this closer after the merge window is closed (can't do anything until then), but do these changes actually solve your contention problem? You don't say so here, so it's hard to tell. thanks, greg k-h