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Date:      Mon, 22 Oct 2018 17:04:05 +0000 (UTC)
From:      Mark Johnston <markj@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r339601 - head/sys/vm
Message-ID:  <201810221704.w9MH45a7091439@repo.freebsd.org>
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Author: markj
Date: Mon Oct 22 17:04:04 2018
New Revision: 339601
URL: https://svnweb.freebsd.org/changeset/base/339601

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

Modified:
  head/sys/vm/vm_glue.c
  head/sys/vm/vm_swapout.c

Modified: head/sys/vm/vm_glue.c
==============================================================================
--- head/sys/vm/vm_glue.c	Mon Oct 22 16:21:50 2018	(r339600)
+++ head/sys/vm/vm_glue.c	Mon Oct 22 17:04:04 2018	(r339601)
@@ -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
 
 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);
 
@@ -367,6 +368,17 @@ vm_thread_new(struct thread *td, int pages)
 		printf("vm_thread_new: kstack allocation failed\n");
 		vm_object_deallocate(ksobj);
 		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);

Modified: head/sys/vm/vm_swapout.c
==============================================================================
--- head/sys/vm/vm_swapout.c	Mon Oct 22 16:21:50 2018	(r339600)
+++ head/sys/vm/vm_swapout.c	Mon Oct 22 17:04:04 2018	(r339601)
@@ -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);
 }

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