From Linus Torvalds <> Date Wed, 22 Jun 2011 21:28:24 -0700 Subject Re: Linux 3.0-rc4 On Wed, Jun 22, 2011 at 1:08 PM, Andi Kleen <andi@firstfloor.org> wrote:

> Linus Torvalds <torvalds@linux-foundation.org> writes:

>

>> and the

>> conversion from spinlocks to mutexes for the anon_vma locking ended up

>> causing a scalability issue that required fixing.

>

> FWIW it's still ~16% slower. Does that count as fixed?



Well, so far I haven't really seen any suggestions on how to improve

it much further.



3.0 will still be noticeably faster than 2.6.39 due to the other

changes made (ie the read-ahead), so yes, the regression itself is

fixed.



But performance on that particular benchmark with that particular

machine is clearly not optimal, in that there are known setups that

would be faster still.



Of course, the reason for the mutex conversion was _other_ loads,

where the spinlocks had bad behavior. So it's a balancing act. And I

suspect we've reached a reasonable point in that balancing, yes.



Linus





