[Qemu-devel] [PATCH 3/8] memory: reorder MemoryRegion fields

[Paolo Bonzini <pbonzini@redhat.com>]

Order fields so that all fields accessed during a RAM read/write fit in
the same cache line.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 include/exec/memory.h | 24 ++++++++++++++----------
 1 file changed, 14 insertions(+), 10 deletions(-)

diff --git a/include/exec/memory.h b/include/exec/memory.h
index 9bbd247..5b1fd12 100644
--- a/include/exec/memory.h
+++ b/include/exec/memory.h
@@ -159,27 +159,32 @@ typedef struct MemoryRegionIoeventfd MemoryRegionIoeventfd;
 
 struct MemoryRegion {
     Object parent_obj;
+
     /* All fields are private - violators will be prosecuted */
-    const MemoryRegionOps *ops;
+
+    /* The following fields should fit in a cache line */
+    bool romd_mode;
+    bool ram;
+    bool subpage;
+    bool readonly; /* For RAM regions */
+    bool rom_device;
+    bool flush_coalesced_mmio;
+    bool global_locking;
+    uint8_t dirty_log_mask;
+    ram_addr_t ram_addr;
     const MemoryRegionIOMMUOps *iommu_ops;
+
+    const MemoryRegionOps *ops;
     void *opaque;
     MemoryRegion *container;
     Int128 size;
     hwaddr addr;
     void (*destructor)(MemoryRegion *mr);
-    ram_addr_t ram_addr;
     uint64_t align;
-    bool subpage;
     bool terminates;
-    bool romd_mode;
-    bool ram;
     bool skip_dump;
-    bool readonly; /* For RAM regions */
     bool enabled;
-    bool rom_device;
     bool warning_printed; /* For reservations */
-    bool flush_coalesced_mmio;
-    bool global_locking;
     uint8_t vga_logging_count;
     MemoryRegion *alias;
     hwaddr alias_offset;
@@ -189,7 +194,6 @@ struct MemoryRegion {
     QTAILQ_ENTRY(MemoryRegion) subregions_link;
     QTAILQ_HEAD(coalesced_ranges, CoalescedMemoryRange) coalesced;
     const char *name;
-    uint8_t dirty_log_mask;
     unsigned ioeventfd_nb;
     MemoryRegionIoeventfd *ioeventfds;
     NotifierList iommu_notify;
-- 
2.5.0