From: John Hubbard <jhubbard@nvidia.com>
To: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: "Andrew Morton" <akpm@linux-foundation.org>,
"Al Viro" <viro@zeniv.linux.org.uk>,
"Christoph Hellwig" <hch@infradead.org>,
"Dan Williams" <dan.j.williams@intel.com>,
"Dave Chinner" <david@fromorbit.com>,
"Ira Weiny" <ira.weiny@intel.com>, "Jan Kara" <jack@suse.cz>,
"Jason Gunthorpe" <jgg@ziepe.ca>,
"Jonathan Corbet" <corbet@lwn.net>,
"Jérôme Glisse" <jglisse@redhat.com>,
"Michal Hocko" <mhocko@suse.com>,
"Mike Kravetz" <mike.kravetz@oracle.com>,
"Shuah Khan" <shuah@kernel.org>,
"Vlastimil Babka" <vbabka@suse.cz>,
"Matthew Wilcox" <willy@infradead.org>,
linux-doc@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-kselftest@vger.kernel.org, linux-rdma@vger.kernel.org,
linux-mm@kvack.org, LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v3 10/12] mm/gup: /proc/vmstat: pin_user_pages (FOLL_PIN) reporting
Date: Mon, 3 Feb 2020 13:34:57 -0800 [thread overview]
Message-ID: <0a81878a-1f7f-daec-0833-d5b91d197ddf@nvidia.com> (raw)
In-Reply-To: <20200203213022.rltjlohvaswk32ln@box.shutemov.name>
On 2/3/20 1:30 PM, Kirill A. Shutemov wrote:
> On Mon, Feb 03, 2020 at 01:04:04PM -0800, John Hubbard wrote:
>> On 2/3/20 5:53 AM, Kirill A. Shutemov wrote:
>>> On Fri, Jan 31, 2020 at 07:40:27PM -0800, John Hubbard wrote:
>>>> diff --git a/mm/gup.c b/mm/gup.c
>>>> index c10d0d051c5b..9fe61d15fc0e 100644
>>>> --- a/mm/gup.c
>>>> +++ b/mm/gup.c
>>>> @@ -29,6 +29,19 @@ struct follow_page_context {
>>>> unsigned int page_mask;
>>>> };
>>>>
>>>> +#ifdef CONFIG_DEBUG_VM
>>>
>>> Why under CONFIG_DEBUG_VM? There's nothing about this in the cover letter.
>>>
>>
>> Early on, gup_benchmark showed a really significant slowdown from using these
>> counters. And I don't doubt that it's still the case.
>>
>> I'll re-measure and add a short summary and a few numbers to the patch commit
>> description, and to the v4 cover letter.
>
> Looks like you'll show zeros for these counters if debug is off. It can be
> confusing to the user. I think these counters should go away if you don't
> count them.
>
OK, that's a good point. (And in fact, the counters==0 situation already led me
astray briefly while debugging with Leon R, even. heh.) I'll remove them entirely for
the !CONFIG_DEBUG_VM case.
thanks,
--
John Hubbard
NVIDIA
next prev parent reply other threads:[~2020-02-03 21:35 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-01 3:40 [PATCH v3 00/12] mm/gup: track FOLL_PIN pages John Hubbard
2020-02-01 3:40 ` [PATCH v3 01/12] mm: dump_page(): better diagnostics for compound pages John Hubbard
2020-02-03 13:16 ` Kirill A. Shutemov
2020-02-03 19:51 ` John Hubbard
2020-02-01 3:40 ` [PATCH v3 02/12] mm/gup: split get_user_pages_remote() into two routines John Hubbard
2020-02-03 13:17 ` Kirill A. Shutemov
2020-02-03 14:20 ` Jan Kara
2020-02-03 21:09 ` John Hubbard
2020-02-01 3:40 ` [PATCH v3 03/12] mm/gup: pass a flags arg to __gup_device_* functions John Hubbard
2020-02-03 13:19 ` Kirill A. Shutemov
2020-02-03 19:56 ` John Hubbard
2020-02-01 3:40 ` [PATCH v3 04/12] mm: introduce page_ref_sub_return() John Hubbard
2020-02-03 13:23 ` Kirill A. Shutemov
2020-02-03 20:03 ` John Hubbard
2020-02-01 3:40 ` [PATCH v3 05/12] mm/gup: pass gup flags to two more routines John Hubbard
2020-02-03 13:24 ` Kirill A. Shutemov
2020-02-03 14:18 ` Jan Kara
2020-02-01 3:40 ` [PATCH v3 06/12] mm/gup: require FOLL_GET for get_user_pages_fast() John Hubbard
2020-02-03 13:26 ` Kirill A. Shutemov
2020-02-03 14:18 ` Jan Kara
2020-02-01 3:40 ` [PATCH v3 07/12] mm/gup: track FOLL_PIN pages John Hubbard
2020-02-03 13:40 ` Kirill A. Shutemov
2020-02-03 21:01 ` John Hubbard
2020-02-03 14:29 ` Jan Kara
2020-02-01 3:40 ` [PATCH v3 08/12] mm/gup: page->hpage_pinned_refcount: exact pin counts for huge pages John Hubbard
2020-02-03 13:45 ` Kirill A. Shutemov
2020-02-03 14:43 ` Jan Kara
2020-02-01 3:40 ` [PATCH v3 09/12] mm: dump_page(): better diagnostics for huge pinned pages John Hubbard
2020-02-03 13:46 ` Kirill A. Shutemov
2020-02-03 14:44 ` Jan Kara
2020-02-01 3:40 ` [PATCH v3 10/12] mm/gup: /proc/vmstat: pin_user_pages (FOLL_PIN) reporting John Hubbard
2020-02-03 13:53 ` Kirill A. Shutemov
2020-02-03 21:04 ` John Hubbard
2020-02-03 21:30 ` Kirill A. Shutemov
2020-02-03 21:34 ` John Hubbard [this message]
2020-02-03 23:16 ` John Hubbard
2020-02-03 23:43 ` John Hubbard
2020-02-01 3:40 ` [PATCH v3 11/12] mm/gup_benchmark: support pin_user_pages() and related calls John Hubbard
2020-02-03 13:58 ` Kirill A. Shutemov
2020-02-03 21:17 ` John Hubbard
2020-02-03 21:55 ` Kirill A. Shutemov
2020-02-03 22:07 ` John Hubbard
2020-02-01 3:40 ` [PATCH v3 12/12] selftests/vm: run_vmtests: invoke gup_benchmark with basic FOLL_PIN coverage John Hubbard
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