From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932115AbVHHQv5 (ORCPT ); Mon, 8 Aug 2005 12:51:57 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932107AbVHHQv5 (ORCPT ); Mon, 8 Aug 2005 12:51:57 -0400 Received: from e35.co.us.ibm.com ([32.97.110.133]:17575 "EHLO e35.co.us.ibm.com") by vger.kernel.org with ESMTP id S932115AbVHHQv4 (ORCPT ); Mon, 8 Aug 2005 12:51:56 -0400 Date: Mon, 8 Aug 2005 22:16:36 +0530 From: Dipankar Sarma To: Manfred Spraul Cc: Andrew Morton , linux-kernel@vger.kernel.org, Hugh Dickins Subject: Re: Fw: two 2.6.13-rc3-mm3 oddities Message-ID: <20050808164636.GA6153@in.ibm.com> Reply-To: dipankar@in.ibm.com References: <20050803095644.78b58cb4.akpm@osdl.org> <20050808140536.GC4558@in.ibm.com> <42F788F8.1000001@colorfullife.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <42F788F8.1000001@colorfullife.com> User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Aug 08, 2005 at 06:31:52PM +0200, Manfred Spraul wrote: > Dipankar Sarma wrote: > > >Hugh, could you please try this with the experimental patch below ? > >Manfred, is it safe to decrement nr_files in file_free() > >instead of the destructor ? I can't see any problem. > > > > > > > The ctor/dtor are only called when new objects are created, not on every > kmem_cache_alloc/kmem_cache_free. Thus I would expect that the counter > becomes negative on builds without CONFIG_DEBUG_SLAB. > Thus increase in the ctor and decrease in file_free() is the wrong > thing. If you want to move the decrease from the dtor to file_free, then > you must move the increase, too. > But: IIRC the counters were moved to the ctor/dtor for performance > reasons, I'd guess mbligh ran into cache line trashing on the > filp_count_lock spinlock with reaim or something like that. Ah, so the whole idea was to inc/dec nr_files less often so that we reduce contention on filp_count_lock, right ? This however causes skews nr_files by the size of the slab array, AFAICS. Since we check nr_files before we allocate files from slab, the check seems inaccurate. Anyway, I guess, I need to look at scaling the file counting first. Thanks Dipankar