Re: [RFC PATCH 0/4] Gang scheduling in CFS

From: Nikunj A Dadhania
Date: Sun Jan 01 2012 - 23:25:03 EST


On Sat, 31 Dec 2011 07:51:15 +0530, Nikunj A Dadhania <nikunj@xxxxxxxxxxxxxxxxxx> wrote:
> On Fri, 30 Dec 2011 15:40:06 +0530, Nikunj A Dadhania <nikunj@xxxxxxxxxxxxxxxxxx> wrote:
> > On Fri, 30 Dec 2011 10:51:47 +0100, Ingo Molnar <mingo@xxxxxxx> wrote:
> > >
> > > * Avi Kivity <avi@xxxxxxxxxx> wrote:
> > >
> > > > [...]
> > > >
> > > > The first part appears to be unrelated to ebizzy itself - it's
> > > > the kunmap_atomic() flushing ptes. It could be eliminated by
> > > > switching to a non-highmem kernel, or by allocating more PTEs
> > > > for kmap_atomic() and batching the flush.
> > >
> > > Nikunj, please only run pure 64-bit/64-bit combinations - by the
> > > time any fix goes upstream and trickles down to distros 32-bit
> > > guests will be even less relevant than they are today.
> > >
> > Sure Ingo, got a 64bit guest working yesterday and I am in process of
> > getting the benchmark numbers for the same.
> >
> Here is the results collected from the 64bit VM runs.
>
[...]

PLE worst case:

>
> dbench 8vm (degraded -8%)
> | dbench| 2.27 | 2.09 | -8 |
[...]
> dbench needs some more love, i will get the perf top caller for
> that.
>

Baseline:
75.18% init [kernel.kallsyms] [k] native_safe_halt
23.32% swapper [kernel.kallsyms] [k] native_safe_halt

Gang V2:
73.21% init [kernel.kallsyms] [k] native_safe_halt
25.74% swapper [kernel.kallsyms] [k] native_safe_halt

That does not give much clue :(
Comments?

> non-PLE - Test Setup:
>
> dbench 8vm (degraded -30%)
> | dbench| 2.01 | 1.38 | -30 |


Baseline:
57.75% init [kernel.kallsyms] [k] native_safe_halt
40.88% swapper [kernel.kallsyms] [k] native_safe_halt

Gang V2:
56.25% init [kernel.kallsyms] [k] native_safe_halt
42.84% swapper [kernel.kallsyms] [k] native_safe_halt

Similar comparison here.

Regards
Nikunj

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