On Fri, Jun 15, 2018 at 02:23:17PM +0200, Jirka Hladky wrote: > I added configurations that used half of the CPUs. However, that would > > mean it fits too nicely within sockets. I've added another set for one > > third of the CPUs and scheduled the tests. Unfortunately, they will not > > complete quickly as my test grid has a massive backlog of work. > > > We always use the number of threads being an integer multiple of the number > of sockets. With another number of threads, we have seen the bigger > variation in results (that's variation between subsequent runs of the same > test). > It's not immediately obvious what's special about those numbers. I did briefly recheck the variability of NAS on one of the machines but the coefficient of variance was usually quite low with occasional outliers of +/- 5% or +/- 7%. Anyway, it's a side-issue. > Nice one, thanks. It's fairly clear that rate limiting may be a major > > component and it's worth testing with the ratelimit increased. Given that > > there have been a lot of improvements on locality and corner cases since > > the rate limit was first introduced, it may also be worth considering > > elimintating the rate limiting entirely and see what falls out. > > > How can we tune mm_numa_migrate_ratelimit? It doesn't seem to be a runtime > tunable nor kernel boot parameter. Could you please share some hints on how > to change it and what value to use? I would be interested to try it out. > It's not runtime tunable I'm afraid. It's a code change and recompile. For example the following allows more pages to be migrated within a 100ms window. diff --git a/mm/migrate.c b/mm/migrate.c index 8c0af0f7cab1..edb550493f06 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -1862,7 +1862,7 @@ static struct page *alloc_misplaced_dst_page(struct page *page, * window of time. Default here says do not migrate more than 1280M per second. */ static unsigned int migrate_interval_millisecs __read_mostly = 100; -static unsigned int ratelimit_pages __read_mostly = 128 << (20 - PAGE_SHIFT); +static unsigned int ratelimit_pages __read_mostly = 512 << (20 - PAGE_SHIFT); /* Returns true if the node is migrate rate-limited after the update */ static bool numamigrate_update_ratelimit(pg_data_t *pgdat, -- Mel Gorman SUSE Labs -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
