linux-kernel - Re: [RFC] autonuma: Migrate on fault among multiple bound nodes

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <87ft7hrvs4.fsf@yhuang-dev.intel.com>
Date:   Thu, 17 Sep 2020 10:18:03 +0800
From:   "Huang\, Ying" <ying.huang@...el.com>
To:     peterz@...radead.org
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        Ingo Molnar <mingo@...hat.com>, Mel Gorman <mgorman@...e.de>,
        Rik van Riel <riel@...hat.com>,
        Johannes Weiner <hannes@...xchg.org>,
        "Matthew Wilcox \(Oracle\)" <willy@...radead.org>,
        Dave Hansen <dave.hansen@...el.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Michal Hocko <mhocko@...e.com>,
        David Rientjes <rientjes@...gle.com>
Subject: Re: [RFC] autonuma: Migrate on fault among multiple bound nodes

peterz@...radead.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