From: Feng Tang <feng.tang@intel.com>
To: Michal Hocko <mhocko@suse.com>
Cc: "linux-mm@kvack.org" <linux-mm@kvack.org>,
Andrew Morton <akpm@linux-foundation.org>,
David Rientjes <rientjes@google.com>,
"Hansen, Dave" <dave.hansen@intel.com>,
"Widawsky, Ben" <ben.widawsky@intel.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-api@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>,
"Williams, Dan J" <dan.j.williams@intel.com>,
"Huang, Ying" <ying.huang@intel.com>,
Dave Hansen <dave.hansen@linux.intel.com>
Subject: Re: [PATCH v6 1/6] mm/mempolicy: Add MPOL_PREFERRED_MANY for multiple preferred nodes
Date: Mon, 2 Aug 2021 19:33:26 +0800 [thread overview]
Message-ID: <20210802113326.GA78980@shbuild999.sh.intel.com> (raw)
In-Reply-To: <YQfTlSy/vmI3ELgR@dhcp22.suse.cz>
On Mon, Aug 02, 2021 at 01:14:29PM +0200, Michal Hocko wrote:
> On Mon 02-08-21 16:11:30, Feng Tang wrote:
> > On Fri, Jul 30, 2021 at 03:18:40PM +0800, Tang, Feng wrote:
> > [snip]
> > > > > One thing is, it's possible that 'nd' is not set in the preferred
> > > > > nodemask.
> > > >
> > > > Yes, and there shouldn't be any problem with that. The given node is
> > > > only used to get the respective zonelist (order distance ordered list of
> > > > zones to try). get_page_from_freelist will then use the preferred node
> > > > mask to filter this zone list. Is that more clear now?
> > >
> > > Yes, from the code, the policy_node() is always coupled with
> > > policy_nodemask(), which secures the 'nodemask' limit. Thanks for
> > > the clarification!
> >
> > Hi Michal,
> >
> > To ensure the nodemask limit, the policy_nodemask() also needs some
> > change to return the nodemask for 'prefer-many' policy, so here is a
> > updated 1/6 patch, which mainly changes the node/nodemask selection
> > for 'prefer-many' policy, could you review it? thanks!
>
> right, I have mixed it with get_policy_nodemask
>
> > @@ -1875,8 +1897,13 @@ static int apply_policy_zone(struct mempolicy *policy, enum zone_type zone)
> > */
> > nodemask_t *policy_nodemask(gfp_t gfp, struct mempolicy *policy)
> > {
> > - /* Lower zones don't get a nodemask applied for MPOL_BIND */
> > - if (unlikely(policy->mode == MPOL_BIND) &&
> > + int mode = policy->mode;
> > +
> > + /*
> > + * Lower zones don't get a nodemask applied for 'bind' and
> > + * 'prefer-many' policies
> > + */
> > + if (unlikely(mode == MPOL_BIND || mode == MPOL_PREFERRED_MANY) &&
> > apply_policy_zone(policy, gfp_zone(gfp)) &&
> > cpuset_nodemask_valid_mems_allowed(&policy->nodes))
> > return &policy->nodes;
>
> Isn't this just too cryptic? Why didn't you simply
> if (mode == MPOL_PREFERRED_MANY)
> return &policy->mode;
>
> in addition to the existing code? I mean why would you even care about
> cpusets? Those are handled at the page allocator layer and will further
> filter the given nodemask.
Ok, I will follow your suggestion and keep 'bind' handling unchanged.
And to be honest, I don't fully understand the current handling for
'bind' policy, will the returning NULL for 'bind' policy open a
sideway for the strict 'bind' limit.
Thanks,
Feng
> --
> Michal Hocko
> SUSE Labs
next prev parent reply other threads:[~2021-08-02 11:33 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 [this message]
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
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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