On Tue, Sep 10, 2024 at 5:30 AM Peter Xu <pet...@redhat.com> wrote:
> On Mon, Sep 09, 2024 at 10:25:36PM +0800, Hyman Huang wrote: > > To activate the periodic CPU throttleing feature, introduce > > the cpu-periodic-throttle. > > > > To control the frequency of throttling, introduce the > > cpu-periodic-throttle-interval. > > > > Signed-off-by: Hyman Huang <yong.hu...@smartx.com> > > Considering that I would still suggest postcopy over auto-converge, IMO we > We are considering the hybrid of precopy and postcopy in fact, and i entirely agree with what you are saying: postcopy migration is an alternative solution to deal with migrations that refuse to converge, or take too long to converge. But enabling this feature may not be easy in production since the recovery requires upper apps to interface, the hugepages and spdk/dpdk scenarios also need to be considered and re-test. Considering auto-converge is the main policy in the industry, the optimization may still make sense. We would like to try to optimize the auto-converge in huge VM case and, IMHO, it doesn't conflict with postcopy. > should be cautious on adding more QMP interfaces on top of auto-converge, > because that means more maintenance burden everywhere.. and it's against > our goal to provide, hopefully, one solution for the long term for > convergence issues. > > Postcopy has a major issue with VFIO, but auto converge isn't anything > better from that regard.. as we can't yet throttle a device so far anyway. > Throttling of DMA probably means DMA faults, then postcopy might be doable > too. Meanwhile we're looking at working out 1G postcopy at some point. > > So I wonder whether we can make any further optmization for auto-converge > (if we still really want that..) to be at least transparent, so that they > Thanks for the advice and of course yes. So, at first, We'll try to avoid adding the new periodic throttle parameter and make it be transparent ? > get auto enabled on new machine types. If we really want some knobs to > control, we can still expose via -global migration.x-* parameters, but then > they'll be all debug tunables only, perhaps that can at least reduce > burdens to QMP maintainers and Libvirt side. > > Thanks, > > -- > Peter Xu > > Yong -- Best regards
