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. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>