On Mon, Jun 10, 2013 at 11:10:29AM -0500, mdroth wrote:
> On Mon, Jun 10, 2013 at 12:14:20PM +0200, Peter Lieven wrote:
> > on incoming migration do not memset pages to zero if they already read as
> > zero.
> > this will allocate a new zero page and consume memory unnecessarily. even
> > if we madvise a MADV_DONTNEED later this will only deallocate the memory
> > asynchronously.
> >
> > Signed-off-by: Peter Lieven <p...@kamp.de>
> > ---
> > arch_init.c | 14 ++++++++------
> > 1 file changed, 8 insertions(+), 6 deletions(-)
> >
> > diff --git a/arch_init.c b/arch_init.c
> > index 08fccf6..cf4e1d5 100644
> > --- a/arch_init.c
> > +++ b/arch_init.c
> > @@ -832,14 +832,16 @@ static int ram_load(QEMUFile *f, void *opaque, int
> > version_id)
> > }
> >
> > ch = qemu_get_byte(f);
> > - memset(host, ch, TARGET_PAGE_SIZE);
> > + if (ch != 0 || !is_zero_page(host)) {
> > + memset(host, ch, TARGET_PAGE_SIZE);
> > #ifndef _WIN32
> > - if (ch == 0 &&
> > - (!kvm_enabled() || kvm_has_sync_mmu()) &&
> > - getpagesize() <= TARGET_PAGE_SIZE) {
> > - qemu_madvise(host, TARGET_PAGE_SIZE, QEMU_MADV_DONTNEED);
> > - }
> > + if (ch == 0 &&
> > + (!kvm_enabled() || kvm_has_sync_mmu()) &&
> > + getpagesize() <= TARGET_PAGE_SIZE) {
> > + qemu_madvise(host, TARGET_PAGE_SIZE,
> > QEMU_MADV_DONTNEED);
> > + }
>
> Reviewed-by: Michael Roth <mdr...@linux.vnet.ibm.com>
>
> Also CC'ing qemu-stable, but from what I gather this just mitigates the
*actually* CC'ing qemu-stable this time :)
