From mboxrd@z Thu Jan 1 00:00:00 1970 From: Carsten Otte Subject: Re: [RFC/PATCH 4/5] loop: execute in place (V2) Date: Wed, 18 May 2005 16:38:38 +0200 Message-ID: <428B536E.6030700@freenet.de> References: <1116422644.2202.1.camel@cotte.boeblingen.de.ibm.com> <1116424432.2202.19.camel@cotte.boeblingen.de.ibm.com> <20050518142849.GC23162@infradead.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, schwidefsky@de.ibm.com, akpm@osdl.org Return-path: Received: from mtagate4.de.ibm.com ([195.212.29.153]:57840 "EHLO mtagate4.de.ibm.com") by vger.kernel.org with ESMTP id S262235AbVEROiw (ORCPT ); Wed, 18 May 2005 10:38:52 -0400 To: Christoph Hellwig In-Reply-To: <20050518142849.GC23162@infradead.org> Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org Christoph Hellwig wrote: >On Wed, May 18, 2005 at 03:53:52PM +0200, Carsten Otte wrote: > > >>[RFC/PATCH 4/5] loop: execute in place (V2) >> >> >> > >This should be ifdef'ed to avoid bloat for non-XIP builds. Or just be dropped >completely. How much difference does it make over read/write and where does >loop performance matter? > > I don't think loop on xip is performance critical. For page cache lookup I see a performance difference of factor 2 on our platform because we have decent memory bandwidth and lock contention slows things down with many CPUs. Given that even without this patch we don't do page cache lookups, I don't think there's much difference. Initially this patch was written for the old loop driver that won't work without this patch... Guess that dropping it is a good idea.