From: Dave Hansen <dave.hansen@intel.com>
To: Davidlohr Bueso <davidlohr@hp.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>,
Andrew Morton <akpm@linux-foundation.org>,
Rik van Riel <riel@redhat.com>, Mel Gorman <mgorman@suse.de>,
Michal Hocko <mhocko@suse.cz>,
"Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
Hugh Dickins <hughd@google.com>,
Davidlohr Bueso <davidlohr.bueso@hp.com>,
David Gibson <david@gibson.dropbear.id.au>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Joonsoo Kim <js1304@gmail.com>,
Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>,
Hillf Danton <dhillf@gmail.com>
Subject: Re: [PATCH v3 00/14] mm, hugetlb: remove a hugetlb_instantiation_mutex
Date: Mon, 31 Mar 2014 11:41:56 -0700 [thread overview]
Message-ID: <5339B6F4.9000809@intel.com> (raw)
In-Reply-To: <1396286773.2507.11.camel@buesod1.americas.hpqcorp.net>
On 03/31/2014 10:26 AM, Davidlohr Bueso wrote:
> On Mon, 2014-03-31 at 09:27 -0700, Dave Hansen wrote:
>> On 12/17/2013 10:53 PM, Joonsoo Kim wrote:
>>> * NOTE for v3
>>> - Updating patchset is so late because of other works, not issue from
>>> this patchset.
>>
>> I've got some folks with a couple TB of RAM seeing long startup times
>> with $LARGE_DATABASE_PRODUCT. It looks to be contention on
>> hugetlb_instantiation_mutex because everyone is trying to zero hugepages
>> under that lock in parallel. Just removing the lock sped things up
>> quite a bit.
>
> Welcome to my world. Regarding the instantiation mutex, it is addressed,
> see commit c999c05ff595 in -next.
Cool stuff. That does seem to fix my parallel-fault hugetlbfs
microbenchmark. I'll recommend that the $DATABASE folks check it as well.
> As for the clear page overhead, I brought this up in lsfmm last week,
> proposing some daemon to clear pages when we have idle cpu... but didn't
> get much positive feedback. Basically (i) not worth the additional
> complexity and (ii) can trigger different application startup times,
> which seems to be something negative. I do have a patch that implements
> huge_clear_page with non-temporal hinting but I didn't see much
> difference on my environment, would you want to give it a try?
I'd just be happy to see it happen outside of the locks. As it stands
now, I have 1 CPU zeroing a huge page, and 159 sitting there sleeping
waiting for it to release the hugetlb_instantiation_mutex. That's just
nonsense. I don't think making them non-temporal will fundamentally
help that. We need them parallelized. According to ftrace, a
hugetlb_fault() takes ~700us. Literally 99% of that is zeroing the page.
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prev parent reply other threads:[~2014-03-31 18:41 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-12-18 6:53 [PATCH v3 00/14] mm, hugetlb: remove a hugetlb_instantiation_mutex Joonsoo Kim
2013-12-18 6:53 ` [PATCH v3 01/14] mm, hugetlb: unify region structure handling Joonsoo Kim
2013-12-21 9:04 ` David Gibson
2014-01-07 2:37 ` Davidlohr Bueso
2013-12-18 6:53 ` [PATCH v3 02/14] mm, hugetlb: region manipulation functions take resv_map rather list_head Joonsoo Kim
2013-12-21 13:43 ` David Gibson
2014-01-07 2:39 ` Davidlohr Bueso
2013-12-18 6:53 ` [PATCH v3 03/14] mm, hugetlb: protect region tracking via newly introduced resv_map lock Joonsoo Kim
2013-12-21 13:58 ` David Gibson
2013-12-23 1:05 ` Joonsoo Kim
2013-12-24 12:00 ` David Gibson
2014-01-06 0:12 ` Joonsoo Kim
2014-01-07 2:39 ` Davidlohr Bueso
2013-12-18 6:53 ` [PATCH v3 04/14] mm, hugetlb: remove resv_map_put() Joonsoo Kim
2013-12-18 6:53 ` [PATCH v3 05/14] mm, hugetlb: make vma_resv_map() works for all mapping type Joonsoo Kim
2013-12-18 6:53 ` [PATCH v3 06/14] mm, hugetlb: remove vma_has_reserves() Joonsoo Kim
2013-12-18 6:53 ` [PATCH v3 07/14] mm, hugetlb: mm, hugetlb: unify chg and avoid_reserve to use_reserve Joonsoo Kim
2013-12-18 6:53 ` [PATCH v3 08/14] mm, hugetlb: call vma_needs_reservation before entering alloc_huge_page() Joonsoo Kim
2013-12-18 6:53 ` [PATCH v3 09/14] mm, hugetlb: remove a check for return value of alloc_huge_page() Joonsoo Kim
2013-12-18 6:53 ` [PATCH v3 10/14] mm, hugetlb: move down outside_reserve check Joonsoo Kim
2013-12-18 6:53 ` [PATCH v3 11/14] mm, hugetlb: move up anon_vma_prepare() Joonsoo Kim
2013-12-18 6:53 ` [PATCH v3 12/14] mm, hugetlb: clean-up error handling in hugetlb_cow() Joonsoo Kim
2013-12-18 6:53 ` [PATCH v3 13/14] mm, hugetlb: retry if failed to allocate and there is concurrent user Joonsoo Kim
2013-12-20 1:02 ` Andrew Morton
2013-12-20 1:58 ` Joonsoo Kim
2013-12-20 2:15 ` Andrew Morton
2013-12-20 5:00 ` Joonsoo Kim
2013-12-20 2:31 ` Davidlohr Bueso
2013-12-20 4:47 ` Joonsoo Kim
2013-12-20 14:01 ` Mel Gorman
2013-12-21 6:48 ` Davidlohr Bueso
2013-12-23 0:44 ` Joonsoo Kim
2013-12-23 2:11 ` Joonsoo Kim
2014-01-03 19:55 ` Davidlohr Bueso
2014-01-06 0:19 ` Joonsoo Kim
2014-01-06 12:19 ` Davidlohr Bueso
2014-01-07 1:57 ` Joonsoo Kim
2014-01-07 2:36 ` Davidlohr Bueso
2014-01-15 3:08 ` David Rientjes
2014-01-15 4:37 ` Davidlohr Bueso
2014-01-15 4:56 ` Andrew Morton
2014-01-15 20:47 ` Davidlohr Bueso
2014-01-15 20:50 ` Andrew Morton
2013-12-18 6:54 ` [PATCH v3 14/14] mm, hugetlb: remove a hugetlb_instantiation_mutex Joonsoo Kim
2014-03-31 16:27 ` [PATCH v3 00/14] " Dave Hansen
2014-03-31 17:26 ` Davidlohr Bueso
2014-03-31 18:41 ` Dave Hansen [this message]
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