From: Michal Hocko <mhocko@suse.com>
To: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
Cc: linux-mm@kvack.org, akpm@linux-foundation.org,
Ben Widawsky <ben.widawsky@intel.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
Feng Tang <feng.tang@intel.com>,
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>,
Huang Ying <ying.huang@intel.com>,
linux-api@vger.kernel.org
Subject: Re: [RFC PATCH] mm/mempolicy: add MPOL_PREFERRED_STRICT memory policy
Date: Wed, 13 Oct 2021 16:22:39 +0200 [thread overview]
Message-ID: <YWbrr2vgLb32JZQ3@dhcp22.suse.cz> (raw)
In-Reply-To: <adc63bf3-b8b6-c705-805d-a84633a7f728@linux.ibm.com>
On Wed 13-10-21 18:40:26, Aneesh Kumar K.V wrote:
> On 10/13/21 18:37, Michal Hocko wrote:
> > On Wed 13-10-21 18:28:40, Aneesh Kumar K.V wrote:
> > > On 10/13/21 18:20, Michal Hocko wrote:
> > [...]
> > > > I am still not sure the semantic makes sense though. Why should
> > > > the lowest node in the nodemask have any special meaning? What if it is
> > > > a node with a higher number that somebody preferes to start with?
> > > >
> > >
> > > That is true. I haven't been able to find an easy way to specify the
> > > preferred node other than expressing it as first node in the node mask. Yes,
> > > it limits the usage of the policy. Any alternate suggestion?
> >
> > set_mempolicy is indeed not very suitable for something you are looking
> > for. Could you be more specific why the initial node is so important?
> > Is this because you want to allocate from a cpu less node first before
> > falling back to others?
> >
>
> One of the reason is that the thread that is faulting in pages first is not
> the one that is going to operate on this page long term. Application wants
> to hint the allocation node for the same reason they use MPOL_PREFERRED now.
Why cannot you move the faulting thread to a numa node of the preference
during the faulting and them move it out if that is really necessary?
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2021-10-13 14:25 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20211013094539.962357-1-aneesh.kumar@linux.ibm.com>
2021-10-13 10:42 ` [RFC PATCH] mm/mempolicy: add MPOL_PREFERRED_STRICT memory policy Michal Hocko
2021-10-13 10:48 ` Michal Hocko
2021-10-13 12:35 ` Aneesh Kumar K.V
2021-10-13 12:50 ` Michal Hocko
2021-10-13 12:58 ` Aneesh Kumar K.V
2021-10-13 13:07 ` Michal Hocko
2021-10-13 13:10 ` Aneesh Kumar K.V
2021-10-13 14:22 ` Michal Hocko [this message]
2021-10-13 13:57 ` Aneesh Kumar K.V
2021-10-13 14:26 ` Michal Hocko
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