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Add uma_zone_get_max() to obtain the effective limit after a call

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to uma_zone_set_max().

The UMA zone limit is not exactly set to the value supplied but
rounded up to completely fill the backing store increment (a page
normally).  This can lead to surprising situations where the number
of elements allocated from UMA is higher than the supplied limit
value.  The new get function reads back the effective value so that
the supplied limit value can be adjusted to the real limit.

Reviewed by:	jeffr
MFC after:	1 week
This commit is contained in:
Andre Oppermann 2010-08-16 14:24:00 +00:00
parent 13852a6e15
commit e49471b04b
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=211396
2 changed files with 30 additions and 0 deletions
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12
sys/vm/uma.h
View File

@ -458,6 +458,18 @@ int uma_zone_set_obj(uma_zone_t zone, struct vm_object *obj, int size);
*/
void uma_zone_set_max(uma_zone_t zone, int nitems);
/*
* Obtains the effective limit on the number of items in a zone
*
* Arguments:
* zone The zone to obtain the effective limit from
*
* Return:
* 0 No limit
* int The effective limit of the zone
*/
int uma_zone_get_max(uma_zone_t zone);
/*
* The following two routines (uma_zone_set_init/fini)
* are used to set the backend init/fini pair which acts on an

18
sys/vm/uma_core.c
View File

@ -2796,6 +2796,24 @@ uma_zone_set_max(uma_zone_t zone, int nitems)
ZONE_UNLOCK(zone);
}
/* See uma.h */
int
uma_zone_get_max(uma_zone_t zone)
{
int nitems;
uma_keg_t keg;
ZONE_LOCK(zone);
keg = zone_first_keg(zone);
if (keg->uk_maxpages)
nitems = keg->uk_maxpages * keg->uk_ipers;
else
nitems = 0;
ZONE_UNLOCK(zone);
return (nitems);
}
/* See uma.h */
void
uma_zone_set_init(uma_zone_t zone, uma_init uminit)