Commit 1d741439 authored by Dr. David Alan Gilbert's avatar Dr. David Alan Gilbert Committed by Juan Quintela
Browse files

Assume madvise for (no)hugepage works 



madvise() returns EINVAL in the case of many failures, but also
returns it in cases where the host kernel doesn't have THP enabled.
Postcopy only really cares that THP is off before it detects faults,
and turns it back on afterwards; so we're going to have
to assume that if the madvise fails then the host just doesn't do
THP and we can carry on with the postcopy.

Signed-off-by: default avatarDr. David Alan Gilbert <dgilbert@redhat.com>
Tested-by: default avatarJason J. Herne <jjherne@linux.vnet.ibm.com>
Reviewed-by: default avatarJuan Quintela <quintela@redhat.com>
Reviewed-by: default avatarAmit Shah <amit.shah@redhat.com>
Signed-off-by: default avatarJuan Quintela <quintela@redhat.com>
parent e85dda80

migration/postcopy-ram.c

+2 −8
Original line number Diff line number Diff line
@@ -241,10 +241,7 @@ static int cleanup_range(const char *block_name, void *host_addr, 
     * We turned off hugepage for the precopy stage with postcopy enabled

     * we can turn it back on now.

     */

    if (qemu_madvise(host_addr, length, QEMU_MADV_HUGEPAGE)) {

        error_report("%s HUGEPAGE: %s", __func__, strerror(errno));

        return -1;

    }

    qemu_madvise(host_addr, length, QEMU_MADV_HUGEPAGE);



    /*

     * We can also turn off userfault now since we should have all the
@@ -345,10 +342,7 @@ static int nhp_range(const char *block_name, void *host_addr, 
     * do delete areas of the page, even if THP thinks a hugepage would

     * be a good idea, so force hugepages off.

     */

    if (qemu_madvise(host_addr, length, QEMU_MADV_NOHUGEPAGE)) {

        error_report("%s: NOHUGEPAGE: %s", __func__, strerror(errno));

        return -1;

    }

    qemu_madvise(host_addr, length, QEMU_MADV_NOHUGEPAGE);



    return 0;

}