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, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>