Horton

Re: many sessions waiting DataFileRead and extend

Tatsuo Ishii <ishii@postgresql.org>

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From: Tatsuo Ishii <ishii@postgresql.org>
To: laurenz.albe@cybertec.at
Cc: jamespang886@gmail.com, frits.hoogland@gmail.com, pgsql-performance@lists.postgresql.org
Date: 2025-06-26T03:25:45Z
Lists: pgsql-performance 
> On Thu, 2025-06-26 at 10:32 +0800, James Pang wrote:
>> thans for you suggestions, we have iowait from sar command too, copy here, checking with infra team not found abnormal IO activities either.  
>> 02:00:01 PM  CPU    %usr   %nice    %sys %iowait    %irq   %soft  %steal  %guest  %gnice   %idle
>> 02:00:03 PM  all   15.92    0.00   43.02    0.65    0.76    2.56    0.00    0.00    0.00   37.09
> 
> Crazy high system time.
> 
> If it is not transparent hugepages, the other suspect is fork().

Can we use starce -S to collect system call statistics to find out
which system call is taking time?

Best regards,
--
Tatsuo Ishii
SRA OSS K.K.
English: http://www.sraoss.co.jp/index_en/
Japanese:http://www.sraoss.co.jp