Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757446AbZFCPD4 (ORCPT ); Wed, 3 Jun 2009 11:03:56 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753587AbZFCPDq (ORCPT ); Wed, 3 Jun 2009 11:03:46 -0400 Received: from x35.xmailserver.org ([64.71.152.41]:51583 "EHLO x35.xmailserver.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753054AbZFCPDp (ORCPT ); Wed, 3 Jun 2009 11:03:45 -0400 X-AuthUser: davidel@xmailserver.org Date: Wed, 3 Jun 2009 07:57:40 -0700 (PDT) From: Davide Libenzi X-X-Sender: davide@makko.or.mcafeemobile.com 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" 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> User-Agent: Alpine 1.10 (DEB 962 2008-03-14) X-GPG-FINGRPRINT: CFAE 5BEE FD36 F65E E640 56FE 0974 BF23 270F 474E X-GPG-PUBLIC_KEY: http://www.xmailserver.org/davidel.asc MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1214 Lines: 30 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 from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/