Re: [RFC] [PATCH] cache pollution aware __copy_from_user_ll()

Hiro Yoshioka
2005-09-02T03:45:58Z

Andrew,

From: Andrew Morton <akpm@osdl.org>
> Andi Kleen <ak@suse.de> wrote:
> >
> > On Friday 02 September 2005 04:08, Andrew Morton wrote:
> >
> > > I suppose I'll queue it up in -mm for a while, although I'm a bit dubious
> > > about the whole idea... We'll gain some and we'll lose some - how do we
> > > know it's a net gain?
> >
> > I suspect it'll gain more than it loses. The only case where it might
> > not gain is immediately someone reading the data from the page cache again
> > after the write.
>
> That's a pretty common case - temporary files.
>
> > But I suppose that's far less frequent than writing the data.
>
> yup.
>
> Hiro, could you please send through a summary of the performance testing
> results sometime? Runtimes rather than oprofile output?

iozone results are

original 2.6.12.4 CPU time = 207.768 sec
cache aware CPU time = 184.783 sec
(three times run)
184.783/207.768=88.94% (11.06% reduction)

original:
pattern9-0-cpu4-0-08191720/iozone.out: CPU Utilization: Wall time 45.997 CPU time 64.527 CPU utilization 140.28 %
pattern9-0-cpu4-0-08191741/iozone.out: CPU Utilization: Wall time 46.878 CPU time 71.933 CPU utilization 153.45 %
pattern9-0-cpu4-0-08191743/iozone.out: CPU Utilization: Wall time 45.152 CPU time 71.308 CPU utilization 157.93 %

cache awre:
pattern9-0-cpu4-0-09011728/iozone.out: CPU Utilization: Wall time 44.842 CPU time 62.465 CPU utilization 139.30 %
pattern9-0-cpu4-0-09011731/iozone.out: CPU Utilization: Wall time 44.718 CPU time 59.273 CPU utilization 132.55 %
pattern9-0-cpu4-0-09011744/iozone.out: CPU Utilization: Wall time 44.367 CPU time 63.045 CPU utilization 142.10 %

Regards,
Hiro