On 6/26/2013 6:37 AM, Ingo Molnar wrote: > > * Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote: > >> On Wed, 26 Jun 2013 11:22:48 +0200 Ingo Molnar <mingo@xxxxxxxxxx> wrote: >> >>> except that on 32 TB >>> systems we don't spend ~2 hours initializing 8,589,934,592 page heads. >> >> That's about a million a second which is crazy slow - even my >> prehistoric desktop is 100x faster than that. >> >> Where's all this time actually being spent? > > See the earlier part of the thread - apparently it's spent initializing > the page heads - remote NUMA node misses from a single boot CPU, going > across a zillion cross-connects? I guess there's some other low hanging > fruits as well - so making this easier to profile would be nice. The > profile posted was not really usable. This is one advantage of delayed memory init. I can do it under the profiler. I will put everything together to accomplish this and then send a perf report. > > Btw., NUMA locality would be another advantage of on-demand > initialization: actual users of RAM tend to allocate node-local > (especially on large clusters), so any overhead will be naturally lower. > > Thanks, > > Ingo > -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
