From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S263790AbTEFPLT (ORCPT ); Tue, 6 May 2003 11:11:19 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S263796AbTEFPLT (ORCPT ); Tue, 6 May 2003 11:11:19 -0400 Received: from e34.co.us.ibm.com ([32.97.110.132]:32226 "EHLO e34.co.us.ibm.com") by vger.kernel.org with ESMTP id S263790AbTEFPLP (ORCPT ); Tue, 6 May 2003 11:11:15 -0400 Date: Tue, 6 May 2003 20:55:55 +0530 From: Dipankar Sarma To: "David S. Miller" Cc: William Lee Irwin III , Andrew Morton , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: 2.5.69-mm1 Message-ID: <20030506152555.GC9875@in.ibm.com> Reply-To: dipankar@in.ibm.com References: <20030504231650.75881288.akpm@digeo.com> <20030505210151.GO8978@holomorphy.com> <20030506110907.GB9875@in.ibm.com> <1052222542.983.27.camel@rth.ninka.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1052222542.983.27.camel@rth.ninka.net> User-Agent: Mutt/1.4i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tue, May 06, 2003 at 05:02:22AM -0700, David S. Miller wrote: > On Tue, 2003-05-06 at 04:09, Dipankar Sarma wrote: > > That brings me to the point - with the fget-speedup patch, we should > > probably change ->file_lock back to an rwlock again. We now take this > > lock only when fd table is shared and under such situation the rwlock > > should help. Andrew, it that ok ? > > rwlocks believe it or not tend not to be superior over spinlocks, > they actually promote cache line thrashing in the case they > are actually being effective (>1 parallel reader) Provided there isn't a very heavy contention among readers for the spin_lock. There is no evidence that this happens with ->file_lock as spin_lock, so I guess we are ok for now. We should probably watch out for some multi-threaded programs (Java->posix-threads ?) on large smp boxes though. Thanks Dipankar