From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail202.messagelabs.com (mail202.messagelabs.com [216.82.254.227]) by kanga.kvack.org (Postfix) with ESMTP id 85C166B0055 for ; Wed, 3 Jun 2009 11:03:50 -0400 (EDT) Received: from makko.or.mcafeemobile.com by x35.xmailserver.org with [XMail 1.26 ESMTP Server] id for from ; Wed, 3 Jun 2009 11:03:32 -0400 Date: Wed, 3 Jun 2009 07:57:40 -0700 (PDT) From: Davide Libenzi Subject: Re: [PATCH 18/23] vfs: Teach epoll to use file_hotplug_lock In-Reply-To: Message-ID: References: <1243893048-17031-18-git-send-email-ebiederm@xmission.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org To: "Eric W. Biederman" Cc: Al Viro , Linux Kernel Mailing List , linux-pci@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, Hugh Dickins , Tejun Heo , Alexey Dobriyan , Linus Torvalds , Alan Cox , Greg Kroah-Hartman , Nick Piggin , Andrew Morton , Christoph Hellwig , "Eric W. Biederman" , "Eric W. Biederman" List-ID: On Tue, 2 Jun 2009, Eric W. Biederman wrote: > I am not clear what problem you have. > > Is it the sprinkling the code that takes and removes the lock? Just > the VFS needs to be involved with that. It is a slightly larger > surface area than doing the work inside the file operations as we > sometimes call the same method from 3-4 different places but it is > definitely a bounded problem. > > Is it putting in the handful lines per subsystem to actually use this > functionality? At that level something generic that is maintained > outside of the subsystem is better than the mess we have with 4-5 > different implementations in the subsystems that need it, each having > a different assortment of bugs. Come on, only in the open fast path, there are at least two spin lock/unlock and two atomic ops. Without even starting to count all the extra branches and software added. Is this stuff *really* needed, or we can faitly happily live w/out? - Davide -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org