Re: [PATCH 0/13] Parallel struct page initialisation v4

[nzimmer]

On an older 8 TB box with lots and lots of cpus the boot time, as 
measure from grub to login prompt, the boot time improved from 1484 
seconds to exactly 1000 seconds.

I have time on 16 TB box tonight and a 12 TB box thursday and will 
hopefully have more numbers then.



On 04/28/2015 11:06 AM, Pekka Enberg wrote:
> On Tue, Apr 28, 2015 at 5:36 PM, Mel Gorman <mgorman@xxxxxxx> wrote:
> > Struct page initialisation had been identified as one of the reasons why
> > large machines take a long time to boot. Patches were posted a long time ago
> > to defer initialisation until they were first used.  This was rejected on
> > the grounds it should not be necessary to hurt the fast paths. This series
> > reuses much of the work from that time but defers the initialisation of
> > memory to kswapd so that one thread per node initialises memory local to
> > that node.
> >
> > After applying the series and setting the appropriate Kconfig variable I
> > see this in the boot log on a 64G machine
> >
> > [    7.383764] kswapd 0 initialised deferred memory in 188ms
> > [    7.404253] kswapd 1 initialised deferred memory in 208ms
> > [    7.411044] kswapd 3 initialised deferred memory in 216ms
> > [    7.411551] kswapd 2 initialised deferred memory in 216ms
> >
> > On a 1TB machine, I see
> >
> > [    8.406511] kswapd 3 initialised deferred memory in 1116ms
> > [    8.428518] kswapd 1 initialised deferred memory in 1140ms
> > [    8.435977] kswapd 0 initialised deferred memory in 1148ms
> > [    8.437416] kswapd 2 initialised deferred memory in 1148ms
> >
> > Once booted the machine appears to work as normal. Boot times were measured
> > from the time shutdown was called until ssh was available again.  In the
> > 64G case, the boot time savings are negligible. On the 1TB machine, the
> > savings were 16 seconds.
> FWIW,
>
> Acked-by: Pekka Enberg <penberg@xxxxxxxxxx>
>
> for the whole series.
>
> - Pekka

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