From: Andrew Morton <akpm@linux-foundation.org>
To: Joonsoo Kim <js1304@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>,
Michal Nazarewicz <mina86@mina86.com>,
Minchan Kim <minchan@kernel.org>,
Mel Gorman <mgorman@techsingularity.net>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
Steven Rostedt <rostedt@goodmis.org>,
Linux Memory Management List <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>,
linux-api@vger.kernel.org, Joonsoo Kim <iamjoonsoo.kim@lge.com>
Subject: Re: [PATCH v4 2/2] mm/page_ref: add tracepoint to track down page reference manipulation
Date: Fri, 4 Mar 2016 12:04:39 -0800 [thread overview]
Message-ID: <20160304120439.a38a15e0fe5b989fe5b8edfc@linux-foundation.org> (raw)
In-Reply-To: <CAAmzW4NwhSKw432qw0Ry+gi=yGpRU-MtC-zQGL27o+XEawLKrg@mail.gmail.com>
On Thu, 3 Mar 2016 16:43:49 +0900 Joonsoo Kim <js1304@gmail.com> wrote:
> > Acked-by: Vlastimil Babka <vbabka@suse.cz>
> >
> >> +config DEBUG_PAGE_REF
> >> + bool "Enable tracepoint to track down page reference manipulation"
> >> + depends on DEBUG_KERNEL
> >> + depends on TRACEPOINTS
> >> + ---help---
> >> + This is the feature to add tracepoint for tracking down page
> >> reference
> >> + manipulation. This tracking is useful to diagnosis functional
> >> failure
> >> + due to migration failure caused by page reference mismatch. Be
> >
> >
> > OK.
> >
> >> + careful to turn on this feature because it could bloat some
> >> kernel
> >> + text. In my configuration, it bloats 30 KB. Although kernel text
> >> will
> >> + be bloated, there would be no runtime performance overhead if
> >> + tracepoint isn't enabled thanks to jump label.
> >
> >
> > I would just write something like:
> >
> > Enabling this feature adds about 30 KB to the kernel code, but runtime
> > performance overhead is virtually none until the tracepoints are actually
> > enabled.
>
> Okay, better!
> Andrew, do you want fixup patch from me or could you simply handle it?
>
This?
--- a/mm/Kconfig.debug~mm-page_ref-add-tracepoint-to-track-down-page-reference-manipulation-fix-3-fix
+++ a/mm/Kconfig.debug
@@ -82,10 +82,9 @@ config DEBUG_PAGE_REF
depends on DEBUG_KERNEL
depends on TRACEPOINTS
---help---
- This is the feature to add tracepoint for tracking down page reference
- manipulation. This tracking is useful to diagnosis functional failure
- due to migration failure caused by page reference mismatch. Be
- careful to turn on this feature because it could bloat some kernel
- text. In my configuration, it bloats 30 KB. Although kernel text will
- be bloated, there would be no runtime performance overhead if
- tracepoint isn't enabled thanks to jump label.
+ This is a feature to add tracepoint for tracking down page reference
+ manipulation. This tracking is useful to diagnose functional failure
+ due to migration failures caused by page reference mismatches. Be
+ careful when enabling this feature because it adds about 30 KB to the
+ kernel code. However the runtime performance overhead is virtually
+ nil until the tracepoints are actually enabled.
_
next prev parent reply other threads:[~2016-03-04 20:04 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-26 0:58 [PATCH v4 1/2] mm: introduce page reference manipulation functions js1304
2016-02-26 0:58 ` [PATCH v4 2/2] mm/page_ref: add tracepoint to track down page reference manipulation js1304
2016-02-26 16:38 ` Steven Rostedt
2016-03-02 16:58 ` Vlastimil Babka
2016-03-03 7:43 ` Joonsoo Kim
2016-03-04 20:04 ` Andrew Morton [this message]
2016-03-07 4:20 ` Joonsoo Kim
2016-03-02 16:44 ` [PATCH v4 1/2] mm: introduce page reference manipulation functions Vlastimil Babka
2016-03-03 7:47 ` Joonsoo Kim
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=20160304120439.a38a15e0fe5b989fe5b8edfc@linux-foundation.org \
--to=akpm@linux-foundation.org \
--cc=iamjoonsoo.kim@lge.com \
--cc=js1304@gmail.com \
--cc=kirill.shutemov@linux.intel.com \
--cc=linux-api@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mgorman@techsingularity.net \
--cc=mina86@mina86.com \
--cc=minchan@kernel.org \
--cc=rostedt@goodmis.org \
--cc=sergey.senozhatsky.work@gmail.com \
--cc=vbabka@suse.cz \
/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).