Messages in this thread | | | Date | Thu, 6 Feb 2014 15:58:17 -0800 (PST) | From | David Rientjes <> | Subject | Re: [RFC PATCH V5] mm readahead: Fix readahead fail for no local memory and limit readahead pages |
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On Thu, 6 Feb 2014, David Rientjes wrote:
> > > > > +#define MAX_REMOTE_READAHEAD 4096UL
> Normally it wouldn't matter because there's no significant downside to it > racing, things like mempolicies which use numa_node_id() extensively would > result in, oops, a page allocation on the wrong node. > > This stands out to me, though, because you're expecting the calculation to > be correct for a specific node. > > The patch is still wrong, though, it should just do > > int node = ACCESS_ONCE(numa_mem_id()); > return min(nr, (node_page_state(node, NR_INACTIVE_FILE) + > node_page_state(node, NR_FREE_PAGES)) / 2); > > since we want to readahead based on the cpu's local node, the comment > saying we're reading ahead onto "remote memory" is wrong since a > memoryless node has local affinity to numa_mem_id(). >
Oops, forgot about the MAX_REMOTE_READAHEAD which needs to be factored in as well, but this handles the bound on local node's statistics.
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