On Sun, Oct 6, 2019 at 4:48 AM Michael S. Tsirkin <mst@xxxxxxxxxx> wrote:
On Sun, Oct 06, 2019 at 10:30:40AM +0200, David Hildenbrand wrote:
> Please note the "use outside of a testing or debugging environment is
> not recommended". Usually you want a "soft" version of this, e.g., via
> the OOM handler (so only drop parts of the cache, not all).
Right. We'll need something softer I guess. By how much, I don't know.
It should be left up to the guest system administrator to configure the trade off between performance and cache memory reclaimed.
And the primary performance metric would be cache hit rate.
So maybe some configuration option that lets you drop cache pages that have a hit rate less than X per minute.
Or more simply: Pages that haven't been hit in the last X seconds.
The other way to do it would be to set a strict cache size limit, but that would be workload dependent and toilsome to tune correctly, so it seems like a worse choice.
--
MST
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