Re: NUMA policy issues with ZONE_MOVABLE

[Christoph Lameter <clameter@sgi.com>]

On Thu, 2 Aug 2007, Mel Gorman wrote:

> Hence the regression test is dependant on timing. The question is if the values
> should always be up-to-date when read from userspace. I put together one patch
> that would refresh the counters when numastat or vmstat was being read but it
> requires a per-cpu function to be called. This may be undesirable as it would
> be punishing on large systems running tools that frequently read /proc/vmstat
> for example. Was it done this way on purpose? The comments around the stats
> code would led me to believe this lag is on purpose to avoid per-cpu calls.

The lag was introduced with the vm statistics rework since ZVCs use 
deferred updates. We could call refresh_vm_stats before handing out the 
counters?

> The alternative was to apply this patch to numactl so that the
> regression test waits on the timers to update. With this patch, the
> regression tests passed on a 4-node x86_64 machine.

Another possible solution. Andi: Which solution would you prefer?

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