2013/11/15 Kevin Wolf <kw...@redhat.com> > 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. > > Will update for this and GETFLAGS & SETFLAGS.
Thanks, Chunyan > Kevin > >
