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| author | Ben Widawsky <ben.widawsky@intel.com> | 2021-09-02 15:00:16 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2021-09-03 09:58:17 -0700 |
| commit | a38a59fdfa10be55d08e4530923d950e739ac6a2 (patch) | |
| tree | 006c2a2e194ec9d39d06ff687df1b1fe3742ac8d /mm/mempolicy.c | |
| parent | cfcaa66f803233c50e17239469f6c96136a673a1 (diff) | |
| download | lwn-a38a59fdfa10be55d08e4530923d950e739ac6a2.tar.gz lwn-a38a59fdfa10be55d08e4530923d950e739ac6a2.zip | |
mm/mempolicy: advertise new MPOL_PREFERRED_MANY
Adds a new mode to the existing mempolicy modes, MPOL_PREFERRED_MANY.
MPOL_PREFERRED_MANY will be adequately documented in the internal
admin-guide with this patch. Eventually, the man pages for mbind(2),
get_mempolicy(2), set_mempolicy(2) and numactl(8) will also have text
about this mode. Those shall contain the canonical reference.
NUMA systems continue to become more prevalent. New technologies like
PMEM make finer grain control over memory access patterns increasingly
desirable. MPOL_PREFERRED_MANY allows userspace to specify a set of nodes
that will be tried first when performing allocations. If those
allocations fail, all remaining nodes will be tried. It's a straight
forward API which solves many of the presumptive needs of system
administrators wanting to optimize workloads on such machines. The mode
will work either per VMA, or per thread.
[Michal Hocko: refine kernel doc for MPOL_PREFERRED_MANY]
Link: https://lore.kernel.org/r/20200630212517.308045-13-ben.widawsky@intel.com
Link: https://lkml.kernel.org/r/1627970362-61305-5-git-send-email-feng.tang@intel.com
Signed-off-by: Ben Widawsky <ben.widawsky@intel.com>
Signed-off-by: Feng Tang <feng.tang@intel.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/mempolicy.c')
| -rw-r--r-- | mm/mempolicy.c | 7 |
1 files changed, 1 insertions, 6 deletions
diff --git a/mm/mempolicy.c b/mm/mempolicy.c index 64be3565ab7f..9e58854d7929 100644 --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -1463,12 +1463,7 @@ static inline int sanitize_mpol_flags(int *mode, unsigned short *flags) *flags = *mode & MPOL_MODE_FLAGS; *mode &= ~MPOL_MODE_FLAGS; - /* - * The check should be 'mode >= MPOL_MAX', but as 'prefer_many' - * is not fully implemented, don't permit it to be used for now, - * and the logic will be restored in following patch - */ - if ((unsigned int)(*mode) >= MPOL_PREFERRED_MANY) + if ((unsigned int)(*mode) >= MPOL_MAX) return -EINVAL; if ((*flags & MPOL_F_STATIC_NODES) && (*flags & MPOL_F_RELATIVE_NODES)) return -EINVAL; |