On 6/16/20 9:09 AM, Andrea Bolognani wrote:
On Thu, 2020-06-11 at 14:00 -0300, Daniel Henrique Barboza wrote:
On Linux, changing the nodeset on 'numatune' does not imply that
the guest memory will be migrated on the spot to the new nodeset.
The memory migration is tied on guest usage of the memory pages,
and an idle guest will take longer to have its memory migrated
to the new nodeset.
This is a behavior explained in detail in the Linux kernel documentation
in Documentation/admin-guide/cgroup-v1/cpusets.rst. The user doesn't
need this level of detail though - just needs his/her expectations
under check. Running 'numastat' and hoping for instant memory
migration from the previous nodeset to the new one is not
viable.
There's also parts of the memory that are locked by QEMU in the
same place, e.g. when VFIO devices are present. Let's also
mention it as another factor that impacts the results the
user might expect from NUMA memory migration with numatune.
Signed-off-by: Daniel Henrique Barboza <danielhb413@xxxxxxxxx>
---
docs/manpages/virsh.rst | 7 +++++++
1 file changed, 7 insertions(+)
I've tweaked the formatting for the manpage and commit message ever
so slightly, added a reference to
https://bugzilla.redhat.com/show_bug.cgi?id=1640869
and pushed. Thanks!
Thanks for the tweaks and pushing. I can't remember now if I totally
forgot to add the bug reference or the bug was locked and I couldn't
link it. Guess I'll have to double check the other patches waiting
for review (TPM proxy, incomplete numa) since they're all tied to
RH bugs ....
Thanks,
DHB
