Commit 137519ce authored by Aurelien Jarno's avatar Aurelien Jarno
Browse files

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: default avatarAurelien Jarno <aurelien@aurel32.net>

git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5839 c046a42c-6fe2-441c-8c8c-71466251a162
parent b8dbdddc

qemu-img.c

+6 −3
Original line number Diff line number Diff line
@@ -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 @@ static BlockDriverState *bdrv_new_open(const char *filename, 
    } 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 @@ static int img_commit(int argc, char **argv) 
    } 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 @@ static int img_info(int argc, char **argv) 
    } 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));