On Mon, Aug 11, 2008 at 4:08 AM, Gerd Hoffmann <kraxel@xxxxxxxxxx> wrote:
Hi,
However, the pvclock_clocksource_read() implementation isDue to the TSC being involved here I don't expect cross-cpu time updates
over-engineered, because it checks for an odd version and uses very
strong rmb() barriers (which generates either an "lfence" or "lock add
$0, (%esp)").
If we're happy to guarantee as an ABI issue that the record will never
be updated cross-cpu, then we can make the barriers simply barrier() and
just check for (src->version != dst->version).
Is that OK with you, or do you want to leave open the possibility of
doing cross-cpu time updates?
will ever happen. IMHO it is fine to change that.
Okay for guest vcpu, but what about physical cpus?
IIRC, the checks are there, and so strict, to account for the
possiblity of the vcpu to be migrated to another cpu in the middle of
the