From: Feng Tang <feng.tang@intel.com>
To: Michal Hocko <mhocko@suse.com>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
Andrea Arcangeli <aarcange@redhat.com>,
David Rientjes <rientjes@google.com>,
Mel Gorman <mgorman@techsingularity.net>,
Mike Kravetz <mike.kravetz@oracle.com>,
Randy Dunlap <rdunlap@infradead.org>,
Vlastimil Babka <vbabka@suse.cz>,
Dave Hansen <dave.hansen@intel.com>,
Ben Widawsky <ben.widawsky@intel.com>,
Andi Kleen <ak@linux.intel.com>,
Dan Williams <dan.j.williams@intel.com>
Subject: Re: [PATCH v4 11/13] mm/mempolicy: huge-page allocation for many preferred
Date: Thu, 15 Apr 2021 15:41:52 +0800 [thread overview]
Message-ID: <20210415074152.GA61572@shbuild999.sh.intel.com> (raw)
In-Reply-To: <YHbtTtEfCICx/yME@dhcp22.suse.cz>
Hi Michal,
Many thanks for reviewing the whole patchset! We will check them.
On Wed, Apr 14, 2021 at 03:25:34PM +0200, Michal Hocko wrote:
> Please use hugetlb prefix to make it explicit that this is hugetlb
> related.
>
> On Wed 17-03-21 11:40:08, Feng Tang wrote:
> > From: Ben Widawsky <ben.widawsky@intel.com>
> >
> > Implement the missing huge page allocation functionality while obeying
> > the preferred node semantics.
> >
> > This uses a fallback mechanism to try multiple preferred nodes first,
> > and then all other nodes. It cannot use the helper function that was
> > introduced because huge page allocation already has its own helpers and
> > it was more LOC, and effort to try to consolidate that.
> >
> > The weirdness is MPOL_PREFERRED_MANY can't be called yet because it is
> > part of the UAPI we haven't yet exposed. Instead of make that define
> > global, it's simply changed with the UAPI patch.
> >
> > [ feng: add NOWARN flag, and skip the direct reclaim to speedup allocation
> > in some case ]
> >
> > Link: https://lore.kernel.org/r/20200630212517.308045-12-ben.widawsky@intel.com
> > Signed-off-by: Ben Widawsky <ben.widawsky@intel.com>
> > Signed-off-by: Feng Tang <feng.tang@intel.com>
> > ---
> > mm/hugetlb.c | 26 +++++++++++++++++++++++---
> > mm/mempolicy.c | 3 ++-
> > 2 files changed, 25 insertions(+), 4 deletions(-)
> >
> > diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> > index 8fb42c6..9dfbfa3 100644
> > --- a/mm/hugetlb.c
> > +++ b/mm/hugetlb.c
> > @@ -1105,7 +1105,7 @@ static struct page *dequeue_huge_page_vma(struct hstate *h,
> > unsigned long address, int avoid_reserve,
> > long chg)
> > {
> > - struct page *page;
> > + struct page *page = NULL;
> > struct mempolicy *mpol;
> > gfp_t gfp_mask;
> > nodemask_t *nodemask;
> > @@ -1126,7 +1126,17 @@ static struct page *dequeue_huge_page_vma(struct hstate *h,
> >
> > gfp_mask = htlb_alloc_mask(h);
> > nid = huge_node(vma, address, gfp_mask, &mpol, &nodemask);
> > - page = dequeue_huge_page_nodemask(h, gfp_mask, nid, nodemask);
> > + if (mpol->mode != MPOL_BIND && nodemask) { /* AKA MPOL_PREFERRED_MANY */
>
> Please use MPOL_PREFERRED_MANY explicitly here.
>
> > + gfp_t gfp_mask1 = gfp_mask | __GFP_NOWARN;
> > +
> > + gfp_mask1 &= ~__GFP_DIRECT_RECLAIM;
> > + page = dequeue_huge_page_nodemask(h,
> > + gfp_mask1, nid, nodemask);
> > + if (!page)
> > + page = dequeue_huge_page_nodemask(h, gfp_mask, nid, NULL);
> > + } else {
> > + page = dequeue_huge_page_nodemask(h, gfp_mask, nid, nodemask);
> > + }
> > if (page && !avoid_reserve && vma_has_reserves(vma, chg)) {
> > SetHPageRestoreReserve(page);
> > h->resv_huge_pages--;
>
> __GFP_DIRECT_RECLAIM handing is not needed here. dequeue_huge_page_nodemask
> only uses gfp mask to get zone and cpusets constraines. So the above
> should have simply been
> if (mpol->mode == MPOL_PREFERRED_MANY) {
> page = dequeue_huge_page_nodemask(h, gfp_mask, nid, nodemask);
> if (page)
> goto got_page;
> /* fallback to all nodes */
> nodemask = NULL;
> }
> page = dequeue_huge_page_nodemask(h, gfp_mask, nid, nodemask);
> got_page:
> if (page ...)
You are right, no need to change the gfp_mask here.
> > @@ -1883,7 +1893,17 @@ struct page *alloc_buddy_huge_page_with_mpol(struct hstate *h,
> > nodemask_t *nodemask;
> >
> > nid = huge_node(vma, addr, gfp_mask, &mpol, &nodemask);
> > - page = alloc_surplus_huge_page(h, gfp_mask, nid, nodemask);
> > + if (mpol->mode != MPOL_BIND && nodemask) { /* AKA MPOL_PREFERRED_MANY */
> > + gfp_t gfp_mask1 = gfp_mask | __GFP_NOWARN;
> > +
> > + gfp_mask1 &= ~__GFP_DIRECT_RECLAIM;
> > + page = alloc_surplus_huge_page(h,
> > + gfp_mask1, nid, nodemask);
> > + if (!page)
> > + alloc_surplus_huge_page(h, gfp_mask, nid, NULL);
> > + } else {
> > + page = alloc_surplus_huge_page(h, gfp_mask, nid, nodemask);
> > + }
>
> And here similar
> if (mpol->mode == MPOL_PREFERRED_MANY) {
> page = alloc_surplus_huge_page(h, (gfp_mask | __GFP_NOWARN) & ~(__GFP_DIRECT_RECLAIM), nodemask);
> if (page)
> goto got_page;
> /* fallback to all nodes */
> nodemask = NULL;
> }
> page = alloc_surplus_huge_page(h, gfp_mask, nodemask);
> got_page:
> > mpol_cond_put(mpol);
>
> You can have a dedicated gfp mask here if you prefer of course but I
> calling out MPOL_PREFERRED_MANY explicitly will make the code easier to
> read.
Will follow. The "if (mpol->mode != MPOL_BIND && nodemask) {
/* AKA MPOL_PREFERRED_MANY *a/ " and "MPOL_MAX + 1" will be replaced
in the 12/13 patch.
Thanks,
Feng
> > return page;
> --
> Michal Hocko
> SUSE Labs
next prev parent reply other threads:[~2021-04-15 7:42 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-17 3:39 [PATCH v4 00/13] Introduced multi-preference mempolicy Feng Tang
2021-03-17 3:39 ` [PATCH v4 01/13] mm/mempolicy: Add comment for missing LOCAL Feng Tang
2021-03-17 3:39 ` [PATCH v4 02/13] mm/mempolicy: convert single preferred_node to full nodemask Feng Tang
2021-04-14 12:17 ` Michal Hocko
2021-03-17 3:40 ` [PATCH v4 03/13] mm/mempolicy: Add MPOL_PREFERRED_MANY for multiple preferred nodes Feng Tang
2021-04-14 12:50 ` Michal Hocko
2021-04-20 7:16 ` Feng Tang
2021-05-13 7:23 ` Feng Tang
2021-05-13 7:25 ` [RFC PATCH 2/2] mempolicy: kill MPOL_F_LOCAL bit Feng Tang
2021-05-13 13:55 ` Andi Kleen
2021-03-17 3:40 ` [PATCH v4 04/13] mm/mempolicy: allow preferred code to take a nodemask Feng Tang
2021-04-14 12:55 ` Michal Hocko
2021-04-19 8:49 ` Feng Tang
2021-03-17 3:40 ` [PATCH v4 05/13] mm/mempolicy: refactor rebind code for PREFERRED_MANY Feng Tang
2021-04-14 12:57 ` Michal Hocko
2021-03-17 3:40 ` [PATCH v4 06/13] mm/mempolicy: kill v.preferred_nodes Feng Tang
2021-04-14 12:58 ` Michal Hocko
2021-03-17 3:40 ` [PATCH v4 07/13] mm/mempolicy: handle MPOL_PREFERRED_MANY like BIND Feng Tang
2021-04-14 13:01 ` Michal Hocko
2021-03-17 3:40 ` [PATCH v4 08/13] mm/mempolicy: Create a page allocator for policy Feng Tang
2021-04-14 13:08 ` Michal Hocko
2021-04-15 8:17 ` Feng Tang
2021-03-17 3:40 ` [PATCH v4 09/13] mm/mempolicy: Thread allocation for many preferred Feng Tang
2021-03-17 3:40 ` [PATCH v4 10/13] mm/mempolicy: VMA " Feng Tang
2021-04-14 13:14 ` Michal Hocko
2021-03-17 3:40 ` [PATCH v4 11/13] mm/mempolicy: huge-page " Feng Tang
2021-03-17 7:19 ` kernel test robot
2021-04-14 13:25 ` Michal Hocko
2021-04-15 7:41 ` Feng Tang [this message]
2021-03-17 3:40 ` [PATCH v4 12/13] mm/mempolicy: Advertise new MPOL_PREFERRED_MANY Feng Tang
2021-03-17 3:40 ` [PATCH v4 13/13] mem/mempolicy: unify mpol_new_preferred() and mpol_new_preferred_many() Feng Tang
2021-04-14 11:21 ` [PATCH v4 00/13] Introduced multi-preference mempolicy Michal Hocko
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