On Mon, Nov 14, 2011 at 03:21:00PM -0800, Andrew Morton wrote: > On Fri, 11 Nov 2011 16:21:19 +0000 > Mel Gorman <mgorman@xxxxxxx> wrote: > > > When min_free_kbytes is updated, some pageblocks are marked MIGRATE_RESERVE. > > Ordinarily, this work is unnoticable as it happens early in boot but on > > large machines with 1TB of memory, this has been reported to delay > > boot times, probably due to the NUMA distances involved. > > > > The bulk of the work is due to calling calling pageblock_is_reserved() > > an unnecessary amount of times and accessing far more struct page > > metadata than is necessary. This patch significantly reduces the > > amount of work done by setup_zone_migrate_reserve() improving boot > > times on 1TB machines. > > > > By how much? :) > > (I mainly ask because I'm curious to know how long the kernel takes to > boot on a 1TB machine...) > Good question. I don't have access to the machine but based on the dmesg they posted before and after, this patch reduced boot times by 27 seconds. With only dmesg, I don't know how long it is taking to start services and mount of the filesystem but assuming no major problems or timeouts from drivers it looks like it is taking about 6 minutes to boot. -- Mel Gorman SUSE Labs -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>