Re: Anticipatory prefaulting in the page fault handler V1

Pavel Machek
2004-12-09T10:57:53Z

Hi!

> Standard Kernel on a 512 Cpu machine allocating 32GB with an increasing
> number of threads (and thus increasing parallellism of page faults):
>
> Gb Rep Threads User System Wall flt/cpu/s fault/wsec
> 32 3 1 1.416s 138.165s 139.050s 45073.831 45097.498
...
> Patched kernel:
>
> Gb Rep Threads User System Wall flt/cpu/s fault/wsec
> 32 3 1 1.098s 138.544s 139.063s 45053.657 45057.920
...
> These number are roughly equal to what can be accomplished with the
> page fault scalability patches.
>
> Kernel patches with both the page fault scalability patches and
> prefaulting:
>
> Gb Rep Threads User System Wall flt/cpu/s fault/wsec
> 32 10 1 4.103s 456.384s 460.046s 45541.992 45544.369
...
>
> The fault rate doubles when both patches are applied.
...
> We are getting into an almost linear scalability in the high end with
> both patches and end up with a fault rate > 3 mio faults per second.

Well, with both patches you also slow single-threaded case more than
twice. What are the effects of this patch on UP system?
Pavel

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