Subject: Re: Additional LWLOCK_STATS statistics
To: Robert Haas <robertmhaas@gmail.com>
References: <55F82AE1.3010407@redhat.com>
 <CA+TgmoYvgL7rA6jBzn60FUeHhb5TH2xu2m9JKPiXFqbZ5Dyi7w@mail.gmail.com>
Cc: "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>
From: Jesper Pedersen <jesper.pedersen@redhat.com>
Organization: JBoss, by Red Hat
Message-ID: <55F871BA.4060404@redhat.com>
Date: Tue, 15 Sep 2015 15:30:02 -0400
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101
 Thunderbird/38.1.0
MIME-Version: 1.0
In-Reply-To: 
 <CA+TgmoYvgL7rA6jBzn60FUeHhb5TH2xu2m9JKPiXFqbZ5Dyi7w@mail.gmail.com>
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Transfer-Encoding: 7bit
Precedence: bulk
Sender: pgsql-hackers-owner@postgresql.org

On 09/15/2015 03:11 PM, Robert Haas wrote:
>> If there is an interest I'll add the patch to the next CommitFest.
>>
>> Thanks for considering, and any feedback is most welcomed.
>
> Seems neat, but I can't understand how to read the flame graphs.
>

X-axis is sort of "up in the air" with flame graphs -- similar call 
stacks are grouped together, and here it is the queue size.

Y-axis is the lock queue size -- e.g. CLogControlLock is "max'ed" out, 
since there is a queue size of 80 with the -c/-j 80 run.

The width of each column shows how the locks are "distributed" within 
the report. Mouse over on the lock name gives the % of the entire 
report, f.ex. CLogControlLock has 74% of spin delays. Note, that some of 
the reports are filtered in order to eliminate "unnecessary" information 
-- see README.

You would need to zoom into some of the information - left click - and 
the reset the zoom afterwards.

I can change the reports if something is more helpful.

Flame graphs for CPU profiling are more common, like

https://dl.dropboxusercontent.com/u/99317937/postgresql/96S-20150808-r30t-17353.svg

Thanks for looking at the patch.

Best regards,
  Jesper


-- 
Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-hackers