[ofa-general] Re: [patch 5/9] Convert anon_vma lock to rw_sem and refcount

[Andrea Arcangeli]

On Tue, Apr 01, 2008 at 01:55:36PM -0700, Christoph Lameter wrote:
>   This results in f.e. the Aim9 brk performance test to got down by 10-15%.

I guess it's more likely because of overscheduling for small crtitical
sections, did you counted the total number of context switches? I
guess there will be a lot more with your patch applied. That
regression is a showstopper and it is the reason why I've suggested
before to add a CONFIG_XPMEM or CONFIG_MMU_NOTIFIER_SLEEP config
option to make the VM locks sleep capable only when XPMEM=y
(PREEMPT_RT will enable it too). Thanks for doing the benchmark work!