Re: DTrace probes patch - Mailing list pgsql-hackers

From Fujii Masao
Subject Re: DTrace probes patch
Date
Msg-id 3f0b79eb0812171926p6f7d5623rbacb9cf769fd36e0@mail.gmail.com
Whole thread Raw
In response to Re: DTrace probes patch  (Robert Lor <Robert.Lor@Sun.COM>)
Responses Re: DTrace probes patch  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-hackers
Hi,

On Thu, Dec 18, 2008 at 4:49 AM, Robert Lor <Robert.Lor@sun.com> wrote:
> Alvaro Herrera wrote:
>>
>> But there are 5 callers of XLogWrite ... why aren't the other ones being
>> tracked too?
>>
>>
>
> This probe originally came from Simon, so it can't possibly be wrong :-)
>
> My understanding is that we only want to track the XLogWrite when advancing
> to the next buffer page, and if there is unwritten data in the new buffer
> page, that indicates no more empty WAL buffer pages available, but I may be
> wrong. I did some tests by adjusting wal_buffers, and I could observe this
> behavior, more calls to XLogWrite with smaller wal_buffers.

I understood your intention. But, I think that its function name is somewhat
confusing.

Regards,

-- 
Fujii Masao
NIPPON TELEGRAPH AND TELEPHONE CORPORATION
NTT Open Source Software Center


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