Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S936224AbZDITe0 (ORCPT ); Thu, 9 Apr 2009 15:34:26 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S933648AbZDITeP (ORCPT ); Thu, 9 Apr 2009 15:34:15 -0400 Received: from one.firstfloor.org ([213.235.205.2]:60628 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757327AbZDITeO (ORCPT ); Thu, 9 Apr 2009 15:34:14 -0400 Date: Thu, 9 Apr 2009 21:36:35 +0200 From: Andi Kleen To: Ingo Molnar Cc: Linus Torvalds , Andi Kleen , Frederic Weisbecker , LKML , Jeff Mahoney , Peter Zijlstra , ReiserFS Development List , Bron Gondwana , Andrew Morton , Alexander Viro Subject: Re: [PATCH] reiserfs: kill-the-BKL Message-ID: <20090409193635.GO14687@one.firstfloor.org> References: <1239070789-13354-1-git-send-email-fweisbec@gmail.com> <87tz4x97uq.fsf@basil.nowhere.org> <20090409184022.GA2665@elte.hu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090409184022.GA2665@elte.hu> User-Agent: Mutt/1.4.2.1i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1453 Lines: 33 > Using a mutex seems like the sane choice here. I'd advocate spinlocks > for a new filesystem any day (but even there it's a fine choice to have > a mutex, if top of the line scalability is not an issue). > > But for a legacy filesystem like reiser3, which depended on the BKL reiser3 is much more widely used in the user base than a lot of "non legacy" file systems. It's very likely it has significantly more users than ext4 for example. Remember that it was the default file system for a major distribution until very recently. I also got a few reiser3 fs still around, it tended to perform very well on kernel hacker workloads. Given all that I think the current performance penalties Frederic reports are not acceptable. Dropping BKL is not a cause in itself, but should just improve performance. > auto-dropping on schedule() it would be rather fragile to use spinlocks, > and it would take forever to validate the result. Not convinced it would be that hard. It could be probably done with some straight forward static code analysis. And after that since there's not much development going anymore it's unlikely to break again. -Andi -- ak@linux.intel.com -- Speaking for myself only. -- 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/