"Martin J. Bligh" wrote:

quoted

running 10,000 tiobench threads I'm showing 23 gigs of
`Commited_AS'.  Is this right?  Those pages are shared,
and if they're not PROT_WRITEable then there's no way in
which they can become unshared?   Seems to be excessively
pessimistic?

Or is 2.5 not up to date?

It's also a global atomic counter that burns up a fair amount
of CPU time bouncing cachelines on the NUMA boxes ... even when
overcommit is set to 1, and it's not used for anything other
than meminfo ... any chance of this either becoming a per-cpu
thing, or dying, or not being used when overcommit is 1?

"It" being vm_committed_space.

The problem is that it's read from frequently, as well as
updated frequently.  So we would still have problems when
we have to reach across and fish the cpu-local counters
out of remote corners of the machine all the time.

The usual tricks for amortising this counter's cost have (serious)
accuracy implications.

I am planning on sitting down and working out exactly what we're
trying to account here - presumably there's another way.  Just
havent got onto it yet.

Worst come to worst, we can hide it inside CONFIG_NOT_WHACKOMATIC
I guess.
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/