On Wed, 2 Jan 2013, Hugh Dickins wrote: > Recent NUMA enhancements are not to blame: this dates back to 2.6.35, > when commit e17f74af351c "mempolicy: don't call mpol_set_nodemask() > when no_context" skipped mpol_parse_str()'s call to mpol_set_nodemask(), > which used to initialize v.preferred_node, or set MPOL_F_LOCAL in flags. > With slab poisoning, you can then rely on mpol_to_str() to set the bit > for node 0x6b6b, probably in the next page above the caller's stack. Ugly. But 2.6.35 means that the patch was not included in several enterprise linux releases. > I don't understand why MPOL_LOCAL is described as a pseudo-policy: > it's a reasonable policy which suffers from a confusing implementation > in terms of MPOL_PREFERRED with MPOL_F_LOCAL. I believe this would be > much more robust if MPOL_LOCAL were recognized in switch statements > throughout, MPOL_F_LOCAL deleted, and MPOL_PREFERRED use the (possibly > empty) nodes mask like everyone else, instead of its preferred_node > variant (I presume an optimization from the days before MPOL_LOCAL). > But that would take me too long to get right and fully tested. The current approaches to implementing NUMA scheduling are making MPOL_LOCAL an explicit policy. See https://patchwork.kernel.org/patch/1703641/. Does that address the concerns? -- 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>