From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:60174) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TLd3p-0001X2-Fw for qemu-devel@nongnu.org; Tue, 09 Oct 2012 12:53:38 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1TLd3n-00055A-RJ for qemu-devel@nongnu.org; Tue, 09 Oct 2012 12:53:37 -0400 Received: from mail-pa0-f45.google.com ([209.85.220.45]:38702) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TLd3n-00054h-LX for qemu-devel@nongnu.org; Tue, 09 Oct 2012 12:53:35 -0400 Received: by mail-pa0-f45.google.com with SMTP id fb10so5369710pad.4 for ; Tue, 09 Oct 2012 09:53:34 -0700 (PDT) Sender: Richard Henderson Message-ID: <5074568C.20602@twiddle.net> Date: Tue, 09 Oct 2012 09:53:32 -0700 From: Richard Henderson MIME-Version: 1.0 References: <1349481605-9561-1-git-send-email-rth@twiddle.net> <20121006101516.GK4623@ohm.aurel32.net> <20121008061747.GE4055@ohm.aurel32.net> In-Reply-To: <20121008061747.GE4055@ohm.aurel32.net> Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH] target-sparc register window handling List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Aurelien Jarno Cc: Blue Swirl , qemu-devel@nongnu.org On 10/07/2012 11:17 PM, Aurelien Jarno wrote: > 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. Confirmed with userland testing (running cc1plus on large input), and I see much more than 4% slow down -- more like 15%. I can reduce this by adding save/restore window inc/dec optimization within the cpu_set_cwp routine, but that only gets me back to 5% slow down. A bit disappointing; I guess other avenues will want exploring. Patch withdrawn. r~