Re: Anticipatory prefaulting in the page fault handler V1

[Pavel Machek]

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

-- 
People were complaining that M$ turns users into beta-testers...
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