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

[Pekka Enberg]

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
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/