On Thu, Jun 19, 2014 at 12:06:44PM +0100, Daniel P. Berrange wrote:
> On Mon, Jun 16, 2014 at 05:08:26PM +0200, Michal Privoznik wrote:
> > +int
> > +virNumaGetPageInfo(int node,
> > + unsigned int page_size,
> > + unsigned int *page_avail,
> > + unsigned int *page_free)
> > +{
> > + int ret = -1;
> > + long system_page_size = sysconf(_SC_PAGESIZE);
> > +
> > + /* sysconf() returns page size in bytes,
> > + * the @page_size is however in kibibytes */
> > + if (page_size == system_page_size / 1024) {
> > + unsigned long long memsize, memfree;
> > +
> > + /* TODO: come up with better algorithm that takes huge pages into
> > + * account. The problem is huge pages cut off regular memory. */
>
> Hmm, so this code is returning normal page count that ignores the fact
> that some pages are not in fact usable because they've been stolen for
> huge pages ? I was thinking that the total memory reported by the kernel
> was reduced when you allocated huage pages, but testing now, it seems I
> was mistaken in that belief. So this is a bit of a nasty gotcha because
> a user of this API would probably expect that the sum of page size *
> page count for all page sizes would equal total physical RAM (give or
> take).
>
> I still like the idea of including the default page size in this info,
> but perhaps we should disable the default system page size for now &
> revisit later if we can figure out a way to accurately report it,
> rather than reporting misleading info.
I should have said, ACK to either #ifdef 0 system page size or ACK to
your previous version of this patch, unless someone has better ideas
to accurately report total + free info for default page sizes.
Regards,
Daniel
--
|: http://berrange.com -o- http://www.flickr.com/photos/dberrange/ :|
|: http://libvirt.org -o- http://virt-manager.org :|
|: http://autobuild.org -o- http://search.cpan.org/~danberr/ :|
|: http://entangle-photo.org -o- http://live.gnome.org/gtk-vnc :|
--
libvir-list mailing list
libvir-list@xxxxxxxxxx
https://www.redhat.com/mailman/listinfo/libvir-list