Messages in this thread | | | Date | Tue, 14 Jun 2016 15:25:07 +0100 | From | Mel Gorman <> | Subject | Re: [PATCH 01/27] mm, vmstat: Add infrastructure for per-node vmstats |
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On Mon, Jun 13, 2016 at 12:26:13PM -0500, Christoph Lameter wrote: > On Thu, 9 Jun 2016, Mel Gorman wrote: > > > VM statistic counters for reclaim decisions are zone-based. If the kernel > > is to reclaim on a per-node basis then we need to track per-node statistics > > but there is no infrastructure for that. The most notable change is that > > There is node_page_state() so the value of any counter per node is already > available. Note that some of the counters (NUMA_xx) for example do not > make much sense as per zone counters and are effectively used as per node > counters. > > So the main effect you are looking for is to have the counters stored in > the per node structure as opposed to the per zone struct in order to > avoid the summing?
Yes.
> Doing so duplicates a large amount of code it seems. >
Also yes. I considered macro magic to cover it but it turned into a major mess. They could always be summed so it would be a minor performance dent and a heavier cache footprint.
> If you do this then also move over certain counters that have more of a > per node use from per zone to per node. Like the NUMA_xxx counters. >
As the NUMA counters are consumed by userspace, I worried that it would break some tools. If the rest of the series gets solidified then I will do it as a single patch on top so it can be reverted if necessary relatively easily.
-- Mel Gorman SUSE Labs
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