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Swap in processes unless there's a global memory shortage.

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On NUMA systems, we would not swap in processes unless all domains
had some free pages.  This is too conservative in general.  Instead,
permit swapins so long as at least one domain has free pages, and add
a kernel stack NUMA policy which ensures that we will try to allocate
kernel stack pages from any domain.

Reported and tested by:	pho, Jan Bramkamp <crest@bultmann.eu>
Reviewed by:	alc, kib
Discussed with:	jeff
MFC after:	3 days
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D17304
This commit is contained in:
markj 2018-10-22 17:04:04 +00:00
parent 782d004253
commit 9ce499cca5
2 changed files with 16 additions and 3 deletions
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14
sys/vm/vm_glue.c
View File

@ -68,6 +68,7 @@ __FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/domainset.h>
#include <sys/limits.h>
#include <sys/lock.h>
#include <sys/malloc.h>
@ -298,7 +299,7 @@ vm_sync_icache(vm_map_t map, vm_offset_t va, vm_offset_t sz)
struct kstack_cache_entry *kstack_cache;
static int kstack_cache_size = 128;
static int kstacks;
static int kstacks, kstack_domain_iter;
static struct mtx kstack_cache_mtx;
MTX_SYSINIT(kstack_cache, &kstack_cache_mtx, "kstkch", MTX_DEF);
@ -369,6 +370,17 @@ vm_thread_new(struct thread *td, int pages)
return (0);
}
/*
* Ensure that kstack objects can draw pages from any memory
* domain. Otherwise a local memory shortage can block a process
* swap-in.
*/
if (vm_ndomains > 1) {
ksobj->domain.dr_policy = DOMAINSET_RR();
ksobj->domain.dr_iter = atomic_fetchadd_int(&kstack_domain_iter,
1);
}
atomic_add_int(&kstacks, 1);
if (KSTACK_GUARD_PAGES != 0) {
pmap_qremove(ks, KSTACK_GUARD_PAGES);

5
sys/vm/vm_swapout.c
View File

@ -742,7 +742,8 @@ swapper_selector(bool wkilled_only)
/*
* Limit swapper to swap in one non-WKILLED process in MAXSLP/2
* interval, assuming that there is:
* - no memory shortage;
* - there exists at least one domain that is not suffering from a shortage of
* free memory;
* - no parallel swap-ins;
* - no other swap-ins in the current SWAPIN_INTERVAL.
*/
@ -750,7 +751,7 @@ static bool
swapper_wkilled_only(void)
{
return (vm_page_count_min() || swap_inprogress > 0 ||
return (vm_page_count_min_set(&all_domains) || swap_inprogress > 0 ||
(u_int)(ticks - last_swapin) < SWAPIN_INTERVAL);
}