Am 15.11.2013 um 06:01 hat Chunyan Liu geschrieben: > Set NOCOW flag to newly created images to solve performance issues on btrfs. > > Btrfs has terrible performance when hosting VM images, even more when the > guest > in those VM are also using btrfs as file system. One way to mitigate this bad > performance is to turn off COW attributes on VM files (since having copy on > write for this kind of data is not useful). > > Signed-off-by: Chunyan Liu <cy...@suse.com>
> diff --git a/include/qemu-common.h b/include/qemu-common.h > index 5054836..fe7dd9b 100644 > --- a/include/qemu-common.h > +++ b/include/qemu-common.h > @@ -50,6 +50,15 @@ > #include "sysemu/os-posix.h" > #endif > > +#ifdef __linux__ > +#include <linux/fs.h> > +#include <sys/ioctl.h> > + > +#ifndef FS_NOCOW_FL > +#define FS_NOCOW_FL 0x00800000 /* Do not cow file */ > +#endif > +#endif > + > #ifndef O_LARGEFILE > #define O_LARGEFILE 0 > #endif hw/block/m25p80.c:219: Fehler: expected identifier before numeric constant On RHEL 6, there seems to be a naming conflict for READ, which is present in linux/fs.h and used as a local enum value by m25p80.c. Kevin