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Re: [Qemu-devel] Debian 7.8.0 SPARC64 on qemu - anything i can do to spe


From: Artyom Tarasenko
Subject: Re: [Qemu-devel] Debian 7.8.0 SPARC64 on qemu - anything i can do to speedup the emulation?
Date: Thu, 30 Jul 2015 10:42:39 +0200

On Thu, Jul 30, 2015 at 10:16 AM, Dennis Luehring <address@hidden> 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

If you are not bound to Linux, try TME
(http://people.csail.mit.edu/fredette/tme/index.html).

Last time I saw it (2010) it was quite faster than QEMU, but was only
able to boot NetBSD (It's probably not hard to add Linux support,
afair if was just missing some ESP commands.).
It doesn't do binary translation but utilizes more host cpu cores.

Otherwise maybe a multi-threaded TCG would help. If it is able to run
translation an execution of code in different threads, it would nearly
double the performance.
Adding mttcg to CC, with a hope to hear from the authors whether their
thread model brings something when emulating a single CPU, or is it
only oriented to SMP machines.

Artyom

-- 
Regards,
Artyom Tarasenko

SPARC and PPC PReP under qemu blog: http://tyom.blogspot.com/search/label/qemu



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