Re: REGRESSION: Performance regressions from switching anon_vma->lock to mutex

Peter Zijlstra
2011-06-15T16:42:11Z

On Wed, 2011-06-15 at 09:18 -0700, Andi Kleen wrote:

> And in general it looks like blind conversion from spinlock to mutex
> is a bad idea right now.

For 4 socket machines, maybe. On 2 sockets I cannot reproduce anything.

I wonder if its the fairness thing, the mutex spinners aren't fifo fair
like the ticket locks are. It could be significant with larger socket
count since their cacheline arbitration is more sucky.