Flip the semantic of M_NOWAIT to only require the allocation to not

sleep, and perform the page allocations with VM_ALLOC_SYSTEM
class. Previously, the allocation was also allowed to completely drain
the reserve of the free pages, being translated to VM_ALLOC_INTERRUPT
request class for vm_page_alloc() and similar functions.

Allow the caller of malloc* to request the 'deep drain' semantic by
providing M_USE_RESERVE flag, now translated to VM_ALLOC_INTERRUPT
class. Previously, it resulted in less aggressive VM_ALLOC_SYSTEM
allocation class.

Centralize the translation of the M_* malloc(9) flags in the single
inline function malloc2vm_flags().

Discussion started by:	"Sears, Steven" <Steven.Sears@netapp.com>
Reviewed by:	alc, mdf (previous version)
Tested by:	pho (previous version)
MFC after:	2 weeks

1 files changed, 16 insertions, 0 deletions

diff --git a/sys/vm/vm_page.h b/sys/vm/vm_page.h
index 76cee03..d9e4692 100644
--- a/sys/vm/vm_page.h
+++ b/sys/vm/vm_page.h
@@ -347,6 +347,22 @@ vm_page_t PHYS_TO_VM_PAGE(vm_paddr_t pa);
 #define	VM_ALLOC_COUNT_SHIFT	16
 #define	VM_ALLOC_COUNT(count)	((count) << VM_ALLOC_COUNT_SHIFT)
 
+#ifdef M_NOWAIT
+static inline int
+malloc2vm_flags(int malloc_flags)
+{
+	int pflags;
+
+	pflags = (malloc_flags & M_USE_RESERVE) != 0 ? VM_ALLOC_INTERRUPT :
+	    VM_ALLOC_SYSTEM;
+	if ((malloc_flags & M_ZERO) != 0)
+		pflags |= VM_ALLOC_ZERO;
+	if ((malloc_flags & M_NODUMP) != 0)
+		pflags |= VM_ALLOC_NODUMP;
+	return (pflags);
+}
+#endif
+
 void vm_page_busy(vm_page_t m);
 void vm_page_flash(vm_page_t m);
 void vm_page_io_start(vm_page_t m);