From: "Huang\, Ying" <ying.huang@intel.com>
To: peterz@infradead.org
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
Ingo Molnar <mingo@redhat.com>, Mel Gorman <mgorman@suse.de>,
Rik van Riel <riel@redhat.com>,
Johannes Weiner <hannes@cmpxchg.org>,
"Matthew Wilcox \(Oracle\)" <willy@infradead.org>,
Dave Hansen <dave.hansen@intel.com>,
Andi Kleen <ak@linux.intel.com>, Michal Hocko <mhocko@suse.com>,
David Rientjes <rientjes@google.com>
Subject: Re: [RFC] autonuma: Migrate on fault among multiple bound nodes
Date: Thu, 17 Sep 2020 10:18:03 +0800 [thread overview]
Message-ID: <87ft7hrvs4.fsf@yhuang-dev.intel.com> (raw)
In-Reply-To: <20200916081052.GI2674@hirez.programming.kicks-ass.net> (peterz@infradead.org's message of "Wed, 16 Sep 2020 10:10:52 +0200")
peterz@infradead.org writes:
> On Wed, Sep 16, 2020 at 08:59:36AM +0800, Huang Ying wrote:
>> +static bool mpol_may_mof(struct mempolicy *pol)
>> +{
>> + /* May migrate among bound nodes for MPOL_BIND */
>> + return pol->flags & MPOL_F_MOF ||
>> + (pol->mode == MPOL_BIND && nodes_weight(pol->v.nodes) > 1);
>> +}
>
> This is weird, why not just set F_MOF on the policy?
>
> In fact, why wouldn't something like:
>
> mbind(.mode=MPOL_BIND, .flags=MPOL_MF_LAZY);
>
> work today? Afaict MF_LAZY will unconditionally result in M_MOF.
Another question.
This means for all VMAs that are mbind() without MPOL_MF_LAZY and tasks
which binds memory via set_mempolicy(), we will not try to optimize
their page placement among the bound nodes even if sysctl knob
kernel.numa_balancing is enabled.
Is this the intended behavior? Although we enable AutoNUMA globally, we
will not try to use it in any places if possible. In some places, it
needs to be enabled again.
Best Regards,
Huang, Ying
next prev parent reply other threads:[~2020-09-17 2:18 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-16 0:59 Huang Ying
2020-09-16 8:10 ` peterz
2020-09-16 8:46 ` Huang, Ying
2020-09-17 2:18 ` Huang, Ying [this message]
2020-09-16 13:39 ` Qian Cai
2020-09-16 15:29 ` David Hildenbrand
2020-09-16 15:35 ` Qian Cai
2020-09-17 3:11 ` Matthew Wilcox
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