[pgpool-hackers: 3248] Re: select(2) storm

[Jesper Pedersen]

Hi,

On 2/19/19 8:33 PM, Tatsuo Ishii wrote:
> Attached is a patch trying eliminate calls to pool_check_fd() (the
> same one I sent to you privately. I just wanted to share with other
> developers).
> 
> The idea is checking select(2) timeout parameter set in a static
> variable in pool_read() and pool_read2(). If it's -1, it means no
> select timeout will be set in pool_check_fd(), which implies we can
> avoid to call pool_check_fd().
> 
> Also I moved pool_check_fd() and friends to pool_stream.c from a
> modularity point of view.
> 


I see a minor speed up and the patch looks good, so I think it is a win 
overall. Please, merge.

> I heard from you that the patch did no performance improvement.  I am
> thinking about it and came to an idea; even if we avoid to call
> pool_check_fd(), subsequent read(2) has to wait for packets from
> frontend or backend. So the total time for processing has not been
> changed by the patch. Of course this is just my guess. I need a proof
> of the theory...
> 

Apparently, 4.20.8 is broken for perf but should be fixed in 4.20.11. 
I'll try and get that installed ASAP.

Then we can look at anything that pops up.

Best regards,
  Jesper