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[PATCH 2/2] vm: make struct vm_map fit into a cache line
From: |
Justus Winter |
Subject: |
[PATCH 2/2] vm: make struct vm_map fit into a cache line |
Date: |
Wed, 30 Apr 2014 21:10:47 +0200 |
Currently, the size of struct vm_map is 68 bytes. By using a bit
field for the boolean flags, it can be made fit into a cache line.
* vm/vm_map.h (struct vm_map): Use a bit field for the boolean flags
wait_for_space and wiring_required.
---
vm/vm_map.h | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/vm/vm_map.h b/vm/vm_map.h
index b6bc177..b8103eb 100644
--- a/vm/vm_map.h
+++ b/vm/vm_map.h
@@ -175,9 +175,12 @@ struct vm_map {
vm_map_entry_t hint; /* hint for quick lookups */
decl_simple_lock_data(, hint_lock) /* lock for hint storage */
vm_map_entry_t first_free; /* First free space hint */
- boolean_t wait_for_space; /* Should callers wait
+
+ /* Flags */
+ unsigned int wait_for_space:1, /* Should callers wait
for space? */
- boolean_t wiring_required;/* All memory wired? */
+ /* boolean_t */ wiring_required:1; /* All memory wired? */
+
unsigned int timestamp; /* Version number */
};
--
1.9.2