On 04.10.19 10:35, Michael S. Tsirkin wrote: > On Fri, Oct 04, 2019 at 10:06:03AM +0200, David Hildenbrand wrote: >> On 04.10.19 01:15, Tyler Sanderson wrote: >>> I was mistaken, the problem with overcommit accounting is not fixed by >>> the change to shrinker interface. >>> This means that large allocations are stopped even if they could succeed >>> by deflating the balloon. >> >> Please note that some people use the balloon for actual memory unplug - >> so initiating to deflate the balloon under any circumstances is >> undesired. It's different with "VIRTIO_BALLOON_F_DEFLATE_ON_OOM" being >> set - however that is barely the case (at least in the setups I know :) ). >> >> So yes, free page reporting is a different thing, because it really is >> used to "hint" and not to "agree to unplug" in any scenario. >> >> -- >> >> Thanks, >> > > > VIRTIO_BALLOON_F_DEFLATE_ON_OOM isn't really well thought through > at the spec level either. For example, when will we inflate again? > Current code does this at the next interrupt, which requires > host to somehow know it's time to inflate. >
The host has access to memory stats of the guest, so it could come up with some heuristics - but I do agree that is not well thought through - one reason why it is barely used :) -- Thanks, David / dhildenb _______________________________________________ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization
