Re: [Bugme-new] [Bug 15618] New: 2.6.18->2.6.32->2.6.33 huge regression in performance

[Anton Starikov <ant.starikov@gmail.com>]

I think we got a winner!

Problem seems to be fixed.

Just for record, I used next patches:

59c33fa7791e9948ba467c2b83e307a0d087ab49
5d0b7235d83eefdafda300656e97d368afcafc9a
1838ef1d782f7527e6defe87e180598622d2d071
4126faf0ab7417fbc6eb99fb0fd407e01e9e9dfe
bafaecd11df15ad5b1e598adc7736afcd38ee13d
0d1622d7f526311d87d7da2ee7dd14b73e45d3fc


Thanks,
Anton.

On Mar 23, 2010, at 8:54 PM, Linus Torvalds wrote:

> 
> 
> On Tue, 23 Mar 2010, Anton Starikov wrote:
> 
>> 
>> On Mar 23, 2010, at 6:45 PM, Linus Torvalds wrote:
>> 
>>> 
>>> 
>>> On Tue, 23 Mar 2010, Ingo Molnar wrote:
>>>> 
>>>> It shows a very brutal amount of page fault invoked mmap_sem spinning 
>>>> overhead.
>>> 
>>> Isn't this already fixed? It's the same old "x86-64 rwsemaphores are using 
>>> the shit-for-brains generic version" thing, and it's fixed by
>>> 
>>> 	1838ef1 x86-64, rwsem: 64-bit xadd rwsem implementation
>>> 	5d0b723 x86: clean up rwsem type system
>>> 	59c33fa x86-32: clean up rwsem inline asm statements
>>> 
>>> NOTE! None of those are in 2.6.33 - they were merged afterwards. But they 
>>> are in 2.6.34-rc1 (and obviously current -git). So Anton would have to 
>>> compile his own kernel to test his load.
>> 
>> 
>> Applied mentioned patches. Things didn't improve too much.
> 
> Yeah, I missed at least one commit, namely
> 
> 	bafaecd x86-64: support native xadd rwsem implementation
> 
> which is the one that actually makes x86-64 able to use the xadd version.
> 
> 		Linus

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