From: John Hubbard <jhubbard@nvidia.com>
To: Daniel Jordan <daniel.m.jordan@oracle.com>,
Anshuman Khandual <anshuman.khandual@arm.com>
Cc: <linux-mm@kvack.org>, <hughd@google.com>,
Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>,
Zi Yan <ziy@nvidia.com>,
Andrew Morton <akpm@linux-foundation.org>,
<linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] mm/vmstat: Add events for PMD based THP migration without split
Date: Mon, 1 Jun 2020 20:20:05 -0700 [thread overview]
Message-ID: <0a936ec7-f44f-1d72-915f-f5758d25fd72@nvidia.com> (raw)
In-Reply-To: <20200601165736.qw5kwwknxltk7bv6@ca-dmjordan1.us.oracle.com>
On 2020-06-01 09:57, Daniel Jordan wrote:
> Hi Anshuman,
>
> On Fri, May 22, 2020 at 09:04:04AM +0530, Anshuman Khandual wrote:
>> This adds the following two new VM events which will help in validating PMD
>> based THP migration without split. Statistics reported through these events
>> will help in performance debugging.
>>
>> 1. THP_PMD_MIGRATION_SUCCESS
>> 2. THP_PMD_MIGRATION_FAILURE
>
> The names suggest a binary event similar to the existing
> pgmigrate_success/fail, but FAILURE only tracks one kind of migration error,
> and then only when the thp is successfully split, so shouldn't it be called
> SPLIT instead?
>
So the full description of the situation, which we're trying to compress into
a shorter name, is "THP pmd migration failure, due to successfully splitting
the THP". From that, the beginning part is the real point here, while the last
part is less important. In other words, the users of these events are people
who are trying to quantify THP migrations, and these events are particularly
relevant for that. The "THP migration failed" is more important here than
the reason that it failed. Or so I believe so far.
So I still think that the names are really quite good, but your point is
also important: maybe this patch should also be tracking other causes
of THP PMD migration failure, in order to get a truer accounting of the
situation.
thanks,
--
John Hubbard
NVIDIA
next prev parent reply other threads:[~2020-06-02 3:20 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-22 3:34 [PATCH] mm/vmstat: Add events for PMD based THP migration without split Anshuman Khandual
2020-06-01 16:57 ` Daniel Jordan
2020-06-02 3:20 ` John Hubbard [this message]
2020-06-02 4:20 ` Anshuman Khandual
2020-06-02 4:48 ` John Hubbard
2020-06-02 5:30 ` Anshuman Khandual
2020-06-02 14:52 ` Daniel Jordan
2020-06-03 4:36 ` Anshuman Khandual
2020-06-03 16:08 ` Daniel Jordan
2020-06-02 15:01 ` Matthew Wilcox
2020-06-03 1:26 ` Anshuman Khandual
2020-06-03 2:57 ` Matthew Wilcox
2020-06-03 4:58 ` Anshuman Khandual
2020-06-03 11:09 ` Matthew Wilcox
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=0a936ec7-f44f-1d72-915f-f5758d25fd72@nvidia.com \
--to=jhubbard@nvidia.com \
--cc=akpm@linux-foundation.org \
--cc=anshuman.khandual@arm.com \
--cc=daniel.m.jordan@oracle.com \
--cc=hughd@google.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=n-horiguchi@ah.jp.nec.com \
--cc=ziy@nvidia.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).