* Alexey Perevalov (a.pereva...@samsung.com) wrote: > On 06/28/2017 10:00 PM, Dr. David Alan Gilbert (git) wrote: > > From: "Dr. David Alan Gilbert" <dgilb...@redhat.com> > > > > Clear the area and turn off THP. > > > > Signed-off-by: Dr. David Alan Gilbert <dgilb...@redhat.com> > > --- > > contrib/libvhost-user/libvhost-user.c | 32 > > ++++++++++++++++++++++++++++++-- > > 1 file changed, 30 insertions(+), 2 deletions(-) > > > > diff --git a/contrib/libvhost-user/libvhost-user.c > > b/contrib/libvhost-user/libvhost-user.c > > index 0658b6e847..ceddeac74f 100644 > > --- a/contrib/libvhost-user/libvhost-user.c > > +++ b/contrib/libvhost-user/libvhost-user.c > > @@ -451,11 +451,39 @@ vu_set_mem_table_exec(VuDev *dev, VhostUserMsg *vmsg) > > } > > if (dev->postcopy_listening) { > > + int ret; > > /* We should already have an open ufd need to mark each memory > > * range as ufd. > > - * Note: Do we need any madvises? Well it's not been accessed > > - * yet, still probably need no THP to be safe, discard to be > > safe? > > */ > > + > > + /* Discard any mapping we have here; note I can't use > > MADV_REMOVE > > + * or fallocate to make the hole since I don't want to lose > > + * data that's already arrived in the shared process. > > + * TODO: How to do hugepage > > + */ > Hi, David, frankly saying, I stuck with my solution, and I have also another > issues, > but here I could suggest solution for hugepages. I think we could transmit a > received pages > bitmap in VHOST_USER_SET_MEM_TABLE (VhostUserMemoryRegion), but it will > raise a compatibility issue, > or introduce special message type for that and send it before > VHOST_USER_SET_MEM_TABLE. > So it will be possible to do fallocate on received bitmap basis, just skip > already copied pages. > If you wish, I could send patches, rebased on yours, for doing it.
What we found works is that actually we don't need to do a discard - since we've only just done the mmap of the arena, nothing will be occupying it on the shared client, so we don't need to discard. We've had a postcopy migrate work now, with a few hacks we're still cleaning up, both on vhost-user-bridge and dpdk; so I'll get this updated and reposted. Dave > > + ret = madvise((void *)dev_region->mmap_addr, > > + dev_region->size + dev_region->mmap_offset, > > + MADV_DONTNEED); > > + if (ret) { > > + fprintf(stderr, > > + "%s: Failed to madvise(DONTNEED) region %d: %s\n", > > + __func__, i, strerror(errno)); > > + } > > + /* Turn off transparent hugepages so we dont get lose wakeups > > + * in neighbouring pages. > > + * TODO: Turn this backon later. > > + */ > > + ret = madvise((void *)dev_region->mmap_addr, > > + dev_region->size + dev_region->mmap_offset, > > + MADV_NOHUGEPAGE); > > + if (ret) { > > + /* Note: This can happen legally on kernels that are > > configured > > + * without madvise'able hugepages > > + */ > > + fprintf(stderr, > > + "%s: Failed to madvise(NOHUGEPAGE) region %d: > > %s\n", > > + __func__, i, strerror(errno)); > > + } > > struct uffdio_register reg_struct; > > /* Note: We might need to go back to using mmap_addr and > > * len + mmap_offset for * huge pages, but then we do hope > > not to > > > -- > Best regards, > Alexey Perevalov -- Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK