Alexander,
On Tue, Nov 19, 2013 at 10:05:53AM +0000, Alexander Motin wrote:
A> Author: mav
A> Date: Tue Nov 19 10:05:53 2013
A> New Revision: 258336
A> URL: http://svnweb.freebsd.org/changeset/base/258336
A>
A> Log:
A> Implement soft pressure on UMA cache bucket sizes.
A>
A> Every time system detects low memory condition decrease bucket sizes for
A> each zone by one item. As result, higher memory pressure will push to
A> smaller bucket sizes and so smaller per-CPU caches and so more efficient
A> memory use.
A>
A> Before this change there was no force to oppose buckets growth as result
A> of practically inevitable zone lock conflicts, and after some run time
A> per-CPU caches could consume enough RAM to kill the system.
Brief review of patch tells me that system never recovers from this. uz_count
it decremented only and never incremented.
A> Modified:
A> head/sys/vm/uma_core.c
A> head/sys/vm/uma_int.h
A>
A> Modified: head/sys/vm/uma_core.c
A>
==============================================================================
A> --- head/sys/vm/uma_core.c Tue Nov 19 09:35:20 2013 (r258335)
A> +++ head/sys/vm/uma_core.c Tue Nov 19 10:05:53 2013 (r258336)
A> @@ -701,6 +701,13 @@ bucket_cache_drain(uma_zone_t zone)
A> bucket_free(zone, bucket, NULL);
A> ZONE_LOCK(zone);
A> }
A> +
A> + /*
A> + * Shrink further bucket sizes. Price of single zone lock collision
A> + * is probably lower then price of global cache drain.
A> + */
A> + if (zone->uz_count > zone->uz_count_min)
A> + zone->uz_count--;
A> }
A>
A> static void
A> @@ -1461,6 +1468,7 @@ zone_ctor(void *mem, int size, void *uda
A> zone->uz_fails = 0;
A> zone->uz_sleeps = 0;
A> zone->uz_count = 0;
A> + zone->uz_count_min = 0;
A> zone->uz_flags = 0;
A> zone->uz_warning = NULL;
A> timevalclear(&zone->uz_ratecheck);
A> @@ -1552,6 +1560,7 @@ out:
A> zone->uz_count = bucket_select(zone->uz_size);
A> else
A> zone->uz_count = BUCKET_MAX;
A> + zone->uz_count_min = zone->uz_count;
A>
A> return (0);
A> }
A>
A> Modified: head/sys/vm/uma_int.h
A>
==============================================================================
A> --- head/sys/vm/uma_int.h Tue Nov 19 09:35:20 2013 (r258335)
A> +++ head/sys/vm/uma_int.h Tue Nov 19 10:05:53 2013 (r258336)
A> @@ -300,7 +300,8 @@ struct uma_zone {
A> volatile u_long uz_fails; /* Total number of alloc failures */
A> volatile u_long uz_frees; /* Total number of frees */
A> uint64_t uz_sleeps; /* Total number of alloc sleeps */
A> - uint16_t uz_count; /* Highest amount of items in bucket */
A> + uint16_t uz_count; /* Amount of items in full bucket */
A> + uint16_t uz_count_min; /* Minimal amount of items there */
A>
A> /* The next three fields are used to print a rate-limited warnings. */
A> const char *uz_warning; /* Warning to print on failure */
--
Totus tuus, Glebius.
_______________________________________________
svn-src-head@freebsd.org mailing list
http://lists.freebsd.org/mailman/listinfo/svn-src-head
To unsubscribe, send any mail to "svn-src-head-unsubscr...@freebsd.org"
