From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:43390) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZKj1E-0000XV-7l for qemu-devel@nongnu.org; Thu, 30 Jul 2015 04:16:49 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZKj19-0004na-09 for qemu-devel@nongnu.org; Thu, 30 Jul 2015 04:16:48 -0400 Received: from mout.gmx.net ([212.227.15.18]:64461) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZKj18-0004nB-LQ for qemu-devel@nongnu.org; Thu, 30 Jul 2015 04:16:42 -0400 References: <55B734A7.8040108@gmx.net> <55B870A9.4090008@gmx.net> <20150729150147.GO11361@aurel32.net> <55B99F95.8010603@gmx.net> <20150730075252.GT11361@aurel32.net> From: Dennis Luehring Message-ID: <55B9DD60.8020801@gmx.net> Date: Thu, 30 Jul 2015 10:16:32 +0200 MIME-Version: 1.0 In-Reply-To: <20150730075252.GT11361@aurel32.net> Content-Type: text/plain; charset=iso-8859-15; format=flowed Content-Transfer-Encoding: 7bit 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: Aurelien Jarno Cc: qemu-devel , Artyom Tarasenko 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 > > Also remember you are comparing apples and oranges there. A GCC compiler > for x86-64 and for SPARC64 can't really be compared, even if the > front-end and middle-end part are the same. The job of generating the > assembly code is not the same and might take more or less time depending > on the architecture complexity. that is true - but its slow even when i compile non-complex stuff, no headers, simple integer math i try to come up with an good example > > Finally make sure you have enough RAM in your guest and that GCC isn't > swapped. Recent GCC versions needs a lot of memory and the default 128MB > might not be enough. > during all my test 70-80% free RAM, no swapping ever