From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:58997) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TL6f9-0000eO-Qk for qemu-devel@nongnu.org; Mon, 08 Oct 2012 02:18:00 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1TL6f8-0000gP-Ky for qemu-devel@nongnu.org; Mon, 08 Oct 2012 02:17:59 -0400 Received: from hall.aurel32.net ([88.191.126.93]:40237) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TL6f8-0000gK-Ej for qemu-devel@nongnu.org; Mon, 08 Oct 2012 02:17:58 -0400 Date: Mon, 8 Oct 2012 08:17:47 +0200 From: Aurelien Jarno Message-ID: <20121008061747.GE4055@ohm.aurel32.net> References: <1349481605-9561-1-git-send-email-rth@twiddle.net> <20121006101516.GK4623@ohm.aurel32.net> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <20121006101516.GK4623@ohm.aurel32.net> Subject: Re: [Qemu-devel] [PATCH] target-sparc register window handling List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Richard Henderson Cc: Blue Swirl , qemu-devel@nongnu.org On Sat, Oct 06, 2012 at 12:15:16PM +0200, Aurelien Jarno wrote: > On Fri, Oct 05, 2012 at 05:00:04PM -0700, Richard Henderson wrote: > > This applies with or without the sparc-compare patch set I > > recently sent, and it works with the same set of tests. > > > > I've not had time to do true benchmarking on this, but it > > does reduce the size of the generated code: > > Experience proves that there is not a direct relation between size of > the generated code and the resulting emulation speed, sometimes smaller > code means slower emulation (when the code generation/optimization takes > too much time), and sometimes bigger code might means faster emulation > (think about replacing some helpers by TCG code). > > As from the user point of view what is important is the emulation speed, > I think benchmarks (even simple ones like measuring the boot time of a > guest) are essential for this kind of patch. > For what it worth, I measure a 4% slow down booting a sparc64 guest on a Core-i5 2500 machine. I guess the memcpy() of the register windows is more expensive that the gain on the TCG side, though it should be probably be confirmed using some profiling tools. -- Aurelien Jarno GPG: 1024D/F1BCDB73 aurelien@aurel32.net http://www.aurel32.net