Re: [Qemu-devel] Significant performance regression in qemu-system-mips.

[Alexander Graf]

On 26.03.2010, at 00:25, Aurelien Jarno wrote:

> On Thu, Mar 25, 2010 at 12:33:33PM -0500, Rob Landley wrote:
>> On Thursday 25 March 2010 04:20:26 Artyom Tarasenko wrote:
>>> 2010/3/24 Rob Landley <address@hidden>:
>>>> I have a native build under qemu that gets killed if it doesn't produce a
>>>> line of output for 60 seconds (hang detection enforced by the host
>>>> monitoring qemu's stdout with --nographic, not from within qemu).
>>>> 
>>>> In the most recent release version, it never came close to triggering on
>>>> mips with a 30 second timeout.  In the current -git version (well, as of
>>>> Thursday anyway), it triggers frequently (about 90% of the time) even
>>>> with a 60 second timeout.
>>> 
>>> Are other platforms affected as well? Do your automated tests run
>>> against qemu-sparc meanwhile?
>> 
>> That was the only platform I hit this particular regression on.  It affects 
>> mips, mipsel, and mips64.
>> 
>> The arm, x86, and x86-64 targets built to the end just fine.
>> 
>> Sparc works fine from a performance perspective (the timeout doesn't 
>> trigger), 
>> it just dies building strace with:
>> 
>>  In file included from file.c:88:^M
>>  /usr/bin/../include/asm/stat.h:56: error: expected specifier-qualifier-list
>>    before 'uid16_t'^
>> 
>> Which is either an strace bug or something wrong with the kernel headers, 
>> either way I need too track that down and fix it.
>> 
>> Powerpc got broken by the 2.6.32->2.6.33 kernel upgrade (the hard drives 
>> don't 
>> work because something broke in DMA interrupt handling, I'm bisecting it), 
>> so 
>> I can't comment on its performance at the moment.  I'll get back to you on 
>> that one.
> 
> This has been broken in r680 of openbios. I haven't found time to find
> the real problem though.

Ugh.

Yeah, I really need to look into it again. It's probably something really 
simple. 99% of the code was if(newworld) conditionized.


Alex