svn commit: r344988 - in stable/12/sys: kern vm

[Mark Johnston]

Author: markj
Date: Mon Mar 11 00:52:55 2019
New Revision: 344988
URL: https://svnweb.freebsd.org/changeset/base/344988

Log:
  MFC r344550:
  Improve vmem tuning for platforms without a direct map.

Modified:
  stable/12/sys/kern/subr_vmem.c
  stable/12/sys/vm/vm_kern.c
Directory Properties:
  stable/12/   (props changed)

Modified: stable/12/sys/kern/subr_vmem.c
==============================================================================
--- stable/12/sys/kern/subr_vmem.c	Sun Mar 10 23:05:38 2019	(r344987)
+++ stable/12/sys/kern/subr_vmem.c	Mon Mar 11 00:52:55 2019	(r344988)
@@ -689,9 +689,11 @@ vmem_startup(void)
 	/*
 	 * Reserve enough tags to allocate new tags.  We allow multiple
 	 * CPUs to attempt to allocate new tags concurrently to limit
-	 * false restarts in UMA.
+	 * false restarts in UMA.  vmem_bt_alloc() allocates from a per-domain
+	 * arena, which may involve importing a range from the kernel arena,
+	 * so we need to keep at least 2 * BT_MAXALLOC tags reserved.
 	 */
-	uma_zone_reserve(vmem_bt_zone, BT_MAXALLOC * (mp_ncpus + 1) / 2);
+	uma_zone_reserve(vmem_bt_zone, 2 * BT_MAXALLOC * mp_ncpus);
 	uma_zone_set_allocf(vmem_bt_zone, vmem_bt_alloc);
 #endif
 }

Modified: stable/12/sys/vm/vm_kern.c
==============================================================================
--- stable/12/sys/vm/vm_kern.c	Sun Mar 10 23:05:38 2019	(r344987)
+++ stable/12/sys/vm/vm_kern.c	Mon Mar 11 00:52:55 2019	(r344988)
@@ -124,8 +124,8 @@ SYSCTL_ULONG(_vm, OID_AUTO, max_kernel_address, CTLFLA
 #if VM_NRESERVLEVEL > 0
 #define	KVA_QUANTUM_SHIFT	(VM_LEVEL_0_ORDER + PAGE_SHIFT)
 #else
-/* On non-superpage architectures want large import sizes. */
-#define	KVA_QUANTUM_SHIFT	(10 + PAGE_SHIFT)
+/* On non-superpage architectures we want large import sizes. */
+#define	KVA_QUANTUM_SHIFT	(8 + PAGE_SHIFT)
 #endif
 #define	KVA_QUANTUM		(1 << KVA_QUANTUM_SHIFT)