From: Anshuman Khandual <anshuman.khandual@arm.com>
To: Daniel Jordan <daniel.m.jordan@oracle.com>,
John Hubbard <jhubbard@nvidia.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: Wed, 3 Jun 2020 10:06:31 +0530 [thread overview]
Message-ID: <db50792c-ced5-a59d-0d94-e1520cf53715@arm.com> (raw)
In-Reply-To: <20200602145208.qucum52lwslhiqff@ca-dmjordan1.us.oracle.com>
On 06/02/2020 08:22 PM, Daniel Jordan wrote:
> On Mon, Jun 01, 2020 at 09:48:09PM -0700, John Hubbard wrote:
>> However, the fact that this is under discussion hints at the need for a
>> bit of documentation help. What do you think about adding some notes about
>> all of this to, say, Documentation/vm/page_migration.rst ?
>
> Yes, that would be good. I understand the intent better now but still think
> the 'failure' event could be misinterpreted as outright failure instead of
> splitting followed by successfully moving the constituent pages.
Does this look okay and sufficient ?
--- a/Documentation/vm/page_migration.rst
+++ b/Documentation/vm/page_migration.rst
@@ -253,5 +253,20 @@ which are function pointers of struct address_space_operations.
PG_isolated is alias with PG_reclaim flag so driver shouldn't use the flag
for own purpose.
+Quantifying Migration
+=====================
+Following events can be used to quantify page migration.
+
+- PGMIGRATE_SUCCESS
+- PGMIGRATE_FAIL
+- THP_MIGRATION_SUCCESS
+- THP_MIGRATION_FAILURE
+
+THP_MIGRATION_FAILURE in particular represents an event when a THP could not be
+migrated as a single entity following an allocation failure and ended up getting
+split into constituent normal pages before being retried. This event, along with
+PGMIGRATE_SUCCESS and PGMIGRATE_FAIL will help in quantifying and analyzing THP
+migration events including both success and failure cases.
+
>
> It might help to clarify in the changelog as well.
>
Sure, will update the commit message accordingly.
next prev parent reply other threads:[~2020-06-03 4:37 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
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 [this message]
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
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