From: Michal Hocko <mhocko@suse.com>
To: Feng Tang <feng.tang@intel.com>
Cc: linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>,
David Rientjes <rientjes@google.com>,
Dave Hansen <dave.hansen@intel.com>,
Ben Widawsky <ben.widawsky@intel.com>,
linux-kernel@vger.kernel.org, linux-api@vger.kernel.org,
Andrea Arcangeli <aarcange@redhat.com>,
Mel Gorman <mgorman@techsingularity.net>,
Mike Kravetz <mike.kravetz@oracle.com>,
Randy Dunlap <rdunlap@infradead.org>,
Vlastimil Babka <vbabka@suse.cz>, Andi Kleen <ak@linux.intel.com>,
Dan Williams <dan.j.williams@intel.com>,
ying.huang@intel.com
Subject: Re: [PATCH v6 5/6] mm/mempolicy: Advertise new MPOL_PREFERRED_MANY
Date: Wed, 28 Jul 2021 14:47:23 +0200 [thread overview]
Message-ID: <YQFR27gkFNqJqzGN@dhcp22.suse.cz> (raw)
In-Reply-To: <1626077374-81682-6-git-send-email-feng.tang@intel.com>
On Mon 12-07-21 16:09:33, Feng Tang wrote:
> From: Ben Widawsky <ben.widawsky@intel.com>
>
> 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.
>
> Link: https://lore.kernel.org/r/20200630212517.308045-13-ben.widawsky@intel.com
> Signed-off-by: Ben Widawsky <ben.widawsky@intel.com>
> Signed-off-by: Feng Tang <feng.tang@intel.com>
> ---
> Documentation/admin-guide/mm/numa_memory_policy.rst | 16 ++++++++++++----
> mm/mempolicy.c | 7 +------
> 2 files changed, 13 insertions(+), 10 deletions(-)
>
> diff --git a/Documentation/admin-guide/mm/numa_memory_policy.rst b/Documentation/admin-guide/mm/numa_memory_policy.rst
> index 067a90a1499c..cd653561e531 100644
> --- a/Documentation/admin-guide/mm/numa_memory_policy.rst
> +++ b/Documentation/admin-guide/mm/numa_memory_policy.rst
> @@ -245,6 +245,14 @@ MPOL_INTERLEAVED
> address range or file. During system boot up, the temporary
> interleaved system default policy works in this mode.
>
> +MPOL_PREFERRED_MANY
> + This mode specifies that the allocation should be attempted from the
> + nodemask specified in the policy. If that allocation fails, the kernel
> + will search other nodes, in order of increasing distance from the first
> + set bit in the nodemask based on information provided by the platform
> + firmware. It is similar to MPOL_PREFERRED with the main exception that
> + is an error to have an empty nodemask.
I believe the target audience of this documents are users rather than
kernel developers and for those the wording might be rather cryptic. I
would rephrase like this
This mode specifices that the allocation should be preferrably
satisfied from the nodemask specified in the policy. If there is
a memory pressure on all nodes in the nodemask the allocation
can fall back to all existing numa nodes. This is effectively
MPOL_PREFERRED allowed for a mask rather than a single node.
With that or similar feel free to add
Acked-by: Michal Hocko <mhocko@suse.com>
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2021-07-28 12:47 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-12 8:09 [PATCH v6 0/6] Introduce multi-preference mempolicy Feng Tang
2021-07-12 8:09 ` [PATCH v6 1/6] mm/mempolicy: Add MPOL_PREFERRED_MANY for multiple preferred nodes Feng Tang
2021-07-28 12:31 ` Michal Hocko
2021-07-28 14:11 ` Feng Tang
2021-07-28 16:12 ` Michal Hocko
2021-07-29 7:09 ` Feng Tang
2021-07-29 13:38 ` Michal Hocko
2021-07-29 15:12 ` Feng Tang
2021-07-29 16:21 ` Michal Hocko
2021-07-30 3:05 ` Feng Tang
2021-07-30 6:36 ` Michal Hocko
2021-07-30 7:18 ` Feng Tang
2021-07-30 7:38 ` Michal Hocko
2021-08-02 8:11 ` Feng Tang
2021-08-02 11:14 ` Michal Hocko
2021-08-02 11:33 ` Feng Tang
2021-08-02 11:47 ` Michal Hocko
2021-07-12 8:09 ` [PATCH v6 2/6] mm/memplicy: add page allocation function for MPOL_PREFERRED_MANY policy Feng Tang
2021-07-28 12:42 ` Michal Hocko
2021-07-28 15:18 ` Feng Tang
2021-07-28 15:25 ` Feng Tang
2021-07-28 16:15 ` Michal Hocko
2021-07-28 16:14 ` Michal Hocko
2021-07-12 8:09 ` [PATCH v6 3/6] mm/mempolicy: enable page allocation for MPOL_PREFERRED_MANY for general cases Feng Tang
2021-07-12 8:09 ` [PATCH v6 4/6] mm/hugetlb: add support for mempolicy MPOL_PREFERRED_MANY Feng Tang
2021-07-21 20:49 ` Mike Kravetz
2021-07-22 8:11 ` Feng Tang
2021-07-22 9:42 ` Michal Hocko
2021-07-22 16:21 ` Mike Kravetz
2021-07-12 8:09 ` [PATCH v6 5/6] mm/mempolicy: Advertise new MPOL_PREFERRED_MANY Feng Tang
2021-07-28 12:47 ` Michal Hocko [this message]
2021-07-28 13:41 ` Feng Tang
2021-07-12 8:09 ` [PATCH v6 6/6] mm/mempolicy: unify the create() func for bind/interleave/prefer-many policies Feng Tang
2021-07-28 12:51 ` Michal Hocko
2021-07-28 13:50 ` Feng Tang
2021-07-15 0:15 ` [PATCH v6 0/6] Introduce multi-preference mempolicy Andrew Morton
2021-07-15 2:13 ` Feng Tang
2021-07-15 18:49 ` Dave Hansen
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