Re: [RFC][PATCH 0/6] Another go at speculative page faults

From: Lai Jiangshan
Date: Thu Oct 23 2014 - 06:37:05 EST


On 10/22/2014 01:56 AM, Peter Zijlstra wrote:
> On Tue, Oct 21, 2014 at 08:09:48PM +0300, Kirill A. Shutemov wrote:
>> It would be interesting to see if the patchset affects non-condended case.
>> Like a one-threaded workload.
>
> It does, and not in a good way, I'll have to look at that... :/

Maybe it is blamed to find_vma_srcu() that it doesn't take the advantage of
the vmacache_find() and cause more cache-misses.


Is it hard to use the vmacache in the find_vma_srcu()?

>
> Performance counter stats for './multi-fault 1' (5 runs):
>
> 73,860,251 page-faults ( +- 0.28% )
> 40,914 cache-misses ( +- 41.26% )
>
> 60.001484913 seconds time elapsed ( +- 0.00% )
>
>
> Performance counter stats for './multi-fault 1' (5 runs):
>
> 70,700,838 page-faults ( +- 0.03% )
> 31,466 cache-misses ( +- 8.62% )
>
> 60.001753906 seconds time elapsed ( +- 0.00% )
> .
>

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