* Rik van Riel <riel@xxxxxxxxxx> [2010-02-04 08:40:43]:
On 02/03/2010 11:12 PM, Balbir Singh wrote:* Rik van Riel<riel@xxxxxxxxxx> [2010-02-03 16:11:03]:I suspect it won't be very many. I have been monitoring
Currently KVM pretends that pages with EPT mappings never gotQuite a clever implementation, one side effect is that one would see a
accessed. This has some side effects in the VM, like swapping
out actively used guest pages and needlessly breaking up actively
used hugepages.
We can avoid those very costly side effects by emulating the
accessed bit for EPT PTEs, which should only be slightly costly
because pages pass through page_referenced infrequently.
larger number of minor faults with EPT enabled and an increase in
allocation/frees of rmap entries, but that can be easily explained.
/proc/meminfo on my system while testing this patch, and
it is quite typical that the size of the inactive anon
list does not change for minutes at a time.
In other words, no pages are moved onto or off of the
inactive anon list for several minutes. That corresponds
to a very small number of minor faults introduced by my
patch.
Of course, when the system is swapping, we will have more
minor faults. However, minor faults should be less of a
performance issue than major faults :)
I do agree with you.