Re: [Qemu-devel] [PATCH] target-sparc: Store mmu index in TB flags

[Richard Henderson <rth@twiddle.net>]

On 08/25/2015 07:37 AM, Dennis Luehring wrote:
> Am 25.08.2015 um 16:25 schrieb Richard Henderson:
>> Er, no, it should.  The primary vector by which I expect improvement is via not
>> encoding dmmu.mmu_primary_context into the TB flags.  I.e. ASI_DMMU, which
>> sun4u certainly uses.
>>
>> The fact that the patch_also_  fixes a sun4v problem is secondary.
>
> please, can you(or someone else) give me a feedback about my tests/numbers -
> and the relevance of them - the stream benchmarks results seems to be worser
> then before and the compilespeed is just a little bit better - so i don't understand (at
> all) what problems are fixed or what is improved now

The fact that stream degraded means that stream is unreliable as a benchmark. 
I suspect that if you simply run it N times with the exact same setup you'll 
see a very large variance in its runtime.

This particular patch cannot possibly have degraded performance, as it could 
only result in a reduction, not expansion, of the number of TBs created.

As to why stream should be unreliable, I have no clue.

> - the compilation test is still 180 times slower then on my host

I'll have to compare that test vs an Alpha guest and see what I get.  I only 
remember one factor of 10, not two...

But you're right, it would be nice to put together a coherent set of 
benchmarks.  Ideally, a guest kernel plus minimal ramdisk with the tests 
pre-loaded so that we can boot and run ./benchmark at the prompt.  That's
the sort of thing we can easily upload to the wiki and share.


r~