From: Baoquan He <bhe@redhat.com>
To: Mike Kravetz <mike.kravetz@oracle.com>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
akpm@linux-foundation.org
Subject: Re: [PATCH 5/5] mm/hugetl.c: warn out if expected count of huge pages adjustment is not achieved
Date: Tue, 21 Jul 2020 17:55:20 +0800 [thread overview]
Message-ID: <20200721095520.GN32539@MiWiFi-R3L-srv> (raw)
In-Reply-To: <c5eb3692-2d05-d6dc-437d-21e51705560e@oracle.com>
On 07/20/20 at 05:38pm, Mike Kravetz wrote:
> On 7/19/20 11:26 PM, Baoquan He wrote:
> > A customer complained that no any message is printed out when failed to
> > allocate explicitly specified number of persistent huge pages. That
> > specifying can be done by writing into /proc/sys/vm/nr_hugepages to
> > increase the persisten huge pages.
> >
> > In the current code, it takes the best effort way to allocate the expected
> > number of huge pages. If only succeeding to get part of them, no any
> > information is printed out.
> >
> > Here try to send out warning message if the expected number of huge pages
> > adjustment is not achieved, including increasing and decreasing the count
> > of persistent huge pages.
>
> Perhaps change the wording a bit,
>
> A customer complained that no message is logged when the number of
> persistent huge pages is not changed to the exact value written to
> the sysfs or proc nr_hugepages file.
>
> In the current code, a best effort is made to satisfy requests made
> via the nr_hugepages file. However, requests may be only partially
> satisfied.
>
> Log a message if the code was unsuccessful in fully satisfying a
> request. This includes both increasing and decreasing the number
> of persistent huge pages.
Thanks, sounds much better, I will use these to replace the old log.
>
> >
> > Signed-off-by: Baoquan He <bhe@redhat.com>
> > ---
> > mm/hugetlb.c | 13 ++++++++++++-
> > 1 file changed, 12 insertions(+), 1 deletion(-)
>
> I am not opposed to this patch. However, I believe the best way for a user
> to determine if their request was successful is to compare the value of
> nr_hugepages to the value which was written.
Agree. While from our customer's request, they told the log can help
'Easily detect and analyse previous reservation failures'.
>
> >
> > diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> > index 467894d8332a..1dfb5d9e4e06 100644
> > --- a/mm/hugetlb.c
> > +++ b/mm/hugetlb.c
> > @@ -2661,7 +2661,7 @@ static int adjust_pool_surplus(struct hstate *h, nodemask_t *nodes_allowed,
> > static int set_max_huge_pages(struct hstate *h, unsigned long count, int nid,
> > nodemask_t *nodes_allowed)
> > {
> > - unsigned long min_count, ret;
> > + unsigned long min_count, ret, old_max;
> > NODEMASK_ALLOC(nodemask_t, node_alloc_noretry, GFP_KERNEL);
> >
> > /*
> > @@ -2723,6 +2723,7 @@ static int set_max_huge_pages(struct hstate *h, unsigned long count, int nid,
> > * pool might be one hugepage larger than it needs to be, but
> > * within all the constraints specified by the sysctls.
> > */
> > + old_max = persistent_huge_pages(h);
> > while (h->surplus_huge_pages && count > persistent_huge_pages(h)) {
> > if (!adjust_pool_surplus(h, nodes_allowed, -1))
> > break;
> > @@ -2779,6 +2780,16 @@ static int set_max_huge_pages(struct hstate *h, unsigned long count, int nid,
> > }
> > out:
> > h->max_huge_pages = persistent_huge_pages(h);
> > + if (count != h->max_huge_pages) {
> > + char buf[32];
> > +
> > + string_get_size(huge_page_size(h), 1, STRING_UNITS_2, buf, 32);
> > + pr_warn("HugeTLB: %s %lu of page size %s failed. Only %s %lu hugepages.\n",
> > + count > old_max ? "increasing" : "decreasing",
> > + abs(count - old_max), buf,
> > + count > old_max ? "increased" : "decreased",
> > + abs(old_max - h->max_huge_pages));
> > + }
> > spin_unlock(&hugetlb_lock);
>
> I would prefer if we drop the lock before logging the message. That would
> involve grabbing the value of h->max_huge_pages before dropping the lock.
Sure, will change. We should try to release the lock's burden. Thanks.
next prev parent reply other threads:[~2020-07-21 9:55 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-20 6:26 [PATCH 0/5] mm/hugetlb: Small cleanup and improvement Baoquan He
2020-07-20 6:26 ` [PATCH 1/5] mm/hugetlb.c: Fix typo of glb_reserve Baoquan He
2020-07-20 22:32 ` Mike Kravetz
2020-07-21 9:17 ` Baoquan He
2020-07-20 6:26 ` [PATCH 2/5] mm/hugetlb.c: make is_hugetlb_entry_hwpoisoned return bool Baoquan He
2020-07-20 22:34 ` Mike Kravetz
2020-07-21 9:56 ` David Hildenbrand
2020-07-20 6:26 ` [PATCH 3/5] mm/hugetlb.c: Remove the unnecessary non_swap_entry() Baoquan He
2020-07-20 22:44 ` Mike Kravetz
2020-07-21 9:56 ` David Hildenbrand
2020-07-20 6:26 ` [PATCH 4/5] doc/vm: fix typo in in the hugetlb admin documentation Baoquan He
2020-07-20 22:55 ` Mike Kravetz
2020-07-21 9:56 ` David Hildenbrand
2020-07-20 6:26 ` [PATCH 5/5] mm/hugetl.c: warn out if expected count of huge pages adjustment is not achieved Baoquan He
2020-07-21 0:38 ` Mike Kravetz
2020-07-21 9:55 ` Baoquan He [this message]
2020-07-22 8:49 ` Baoquan He
2020-07-22 16:15 ` Mike Kravetz
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