From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:53417) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZKjcF-0006wO-VP for qemu-devel@nongnu.org; Thu, 30 Jul 2015 04:55:05 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZKjcE-0006Tp-U4 for qemu-devel@nongnu.org; Thu, 30 Jul 2015 04:55:03 -0400 Received: from hall.aurel32.net ([2001:bc8:30d7:100::1]:35793) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZKjcE-0006T4-OD for qemu-devel@nongnu.org; Thu, 30 Jul 2015 04:55:02 -0400 Date: Thu, 30 Jul 2015 10:55:00 +0200 From: Aurelien Jarno Message-ID: <20150730085500.GV11361@aurel32.net> References: <55B734A7.8040108@gmx.net> <55B870A9.4090008@gmx.net> <20150729150147.GO11361@aurel32.net> <55B99F95.8010603@gmx.net> <20150730075252.GT11361@aurel32.net> <55B9DD60.8020801@gmx.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <55B9DD60.8020801@gmx.net> Subject: Re: [Qemu-devel] Debian 7.8.0 SPARC64 on qemu - anything i can do to speedup the emulation? List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Dennis Luehring Cc: qemu-devel , Artyom Tarasenko On 2015-07-30 10:16, Dennis Luehring wrote: > Am 30.07.2015 um 09:52 schrieb Aurelien Jarno: > >On 2015-07-30 05:52, Dennis Luehring wrote: > >> Am 29.07.2015 um 17:01 schrieb Aurelien Jarno: > >> >The point is that emulation has a cost, and it's quite difficult to > >> >to lower it and thus improve the emulation speed. > >> > >> so its just not strange for you to see an 1/100...200 of the native x64 > >> speed under qemu/SPARC64 > >> i hoped that someone will jump up an shout "its impossible - it needs to be > >> a bug" ...sadly not > > > >Overall the ratio is more around 10, but in some specific cases where > >the TB cache is inefficient and TB can't be linked or with an > >inefficient MMU, a ratio of 100 is possible. > > > sysbench (0.4.12) --num-threads=1 --test=cpu --cpu-max-prime=2000 run > Host x64 : 1.3580s > Qemu SPARC64: 184.2532s > > sysbench shows nearly ration of 200 Note that when you say SPARC64 here, it's actually only the kernel, you are using a 32-bit userland. And that makes a difference. Here are my tests here: host (x86-64) 0.8976s sparc32 guest (sparc64 kernel) 99.6116s sparc64 guest (sparc64 kernel) 4.4908s So it looks like the 32-bit code is not QEMU friendly. I haven't looked at it yet, but I guess it might be due to dynamic jumps, so that TB can't be chained. -- Aurelien Jarno GPG: 4096R/1DDD8C9B aurelien@aurel32.net http://www.aurel32.net