commit 137519ce2e269915de0f67a13ac32b67605cad72
author aurel32 <aurel32@c046a42c-6fe2-441c-8c8c-71466251a162> Sun Nov 30 19:12:49 2008 +0000
committer aurel32 <aurel32@c046a42c-6fe2-441c-8c8c-71466251a162> Sun Nov 30 19:12:49 2008 +0000
tree 0ba6e3dda0eae5d50e96992cfecd073d71acb713
parent b8dbdddc9edda7d64352a837aa77c077c5dc960f

qemu-img: open files with cache=writeback

Data integrity is not important in qemu-img, so open the files with
cache=writeback. This fixes the performance regression seen with qemu-img
since revision 5485, and most particularly with the qcow2 format.

Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>

git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5839 c046a42c-6fe2-441c-8c8c-71466251a162

qemu-img.c

diff --git a/qemu-img.c b/qemu-img.c
index 70c2403..207535f 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -30,6 +30,9 @@
 #include <windows.h>
 #endif
 
+/* Default to cache=writeback as data integrity is not important for qemu-tcg. */
+#define BRDV_O_FLAGS BDRV_O_CACHE_WB
+
 static void __attribute__((noreturn)) error(const char *fmt, ...)
 {
     va_list ap;
@@ -186,7 +189,7 @@
     } else {
         drv = NULL;
     }
-    if (bdrv_open2(bs, filename, 0, drv) < 0) {
+    if (bdrv_open2(bs, filename, BRDV_O_FLAGS, drv) < 0) {
         error("Could not open '%s'", filename);
     }
     if (bdrv_is_encrypted(bs)) {
@@ -317,7 +320,7 @@
     } else {
         drv = NULL;
     }
-    if (bdrv_open2(bs, filename, 0, drv) < 0) {
+    if (bdrv_open2(bs, filename, BRDV_O_FLAGS, drv) < 0) {
         error("Could not open '%s'", filename);
     }
     ret = bdrv_commit(bs);
@@ -691,7 +694,7 @@
     } else {
         drv = NULL;
     }
-    if (bdrv_open2(bs, filename, 0, drv) < 0) {
+    if (bdrv_open2(bs, filename, BRDV_O_FLAGS, drv) < 0) {
         error("Could not open '%s'", filename);
     }
     bdrv_get_format(bs, fmt_name, sizeof(fmt_name));