From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from protonic.prtnl (protonic.xs4all.nl [213.84.116.84]) by ozlabs.org (Postfix) with ESMTP id 2DF77686E9 for ; Thu, 10 Nov 2005 18:48:53 +1100 (EST) Received: from localhost (localhost [127.0.0.1]) by protonic.prtnl (Postfix) with ESMTP id 7945929EBC for ; Thu, 10 Nov 2005 08:47:13 +0100 (CET) Received: from protonic.prtnl ([127.0.0.1]) by localhost (protonic [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 31700-08 for ; Thu, 10 Nov 2005 08:47:12 +0100 (CET) Received: from linux.local (linux.prtnl [192.168.1.97]) by protonic.prtnl (Postfix) with ESMTP id 9FB7C29EBB for ; Thu, 10 Nov 2005 08:47:12 +0100 (CET) From: David Jander To: linuxppc-embedded@ozlabs.org Date: Thu, 10 Nov 2005 09:48:45 +0200 References: <200510302203.25390.pantelis.antoniou@gmail.com> <1131396000.4652.24.camel@gaston> <20051109120450.GB8588@logos.cnet> In-Reply-To: <20051109120450.GB8588@logos.cnet> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Message-Id: <200511100848.46263.david.jander@protonic.nl> Subject: Re: [PATCH 2.6.14] mm: 8xx MM fix for List-Id: Linux on Embedded PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Wednesday 09 November 2005 13:04, Marcelo Tosatti wrote: >[...] > > ** 2.6.14 DataTLBHandler jump direct ("two exceptions"): > > first batch: > avg: 287ms > avg: 287ms > avg: 287ms > avg: 287ms > avg: 287ms > > second batch: > avg: 287ms > avg: 287ms > avg: 287ms > avg: 287ms > avg: 287ms > > ** 2.6.14 vanilla ("three exceptions"): > > first batch: > avg: 288ms > avg: 285ms > avg: 287ms > avg: 287ms > avg: 288ms > > second batch: > avg: 288ms > avg: 288ms > avg: 287ms > avg: 287ms > avg: 287ms > > ** 2.4.17 (root on RAMDISK): > > avg: 309ms > avg: 313ms > avg: 312ms > avg: 311ms > avg: 310ms Hmmm. This is a lot in the line of the tests I did with (the more generic benchmark) nbench. After looking at those results (see my other post in this thread) I already suspected something like this. > The v2.6.14's kernel jump-direct is more consistent at 287ms, > while vanilla 2.6.14 oscillates between 285 and 288ms, but > no significant difference between the two. > > v2.6's fault handling is clearly faster than 2.4's (note that the compiler > is also different, 2.4 uses gcc 2.95 and 2.6 gcc 3.3). I don't think the compiler does much difference here though. In my test the exact same compiler was used for both kernels, and the same rootfs and binary of nbench. gcc-3.3.3. I did also use oprofile to get an idea of where the code spent its most cpu time during nbench, and AFAIR flush_dcache_icache() took quite a chunk of it, so I assume page fault latency is of importance there too, and might account for the huge difference between 2.4 and 2.6. Greetings, -- David Jander