Re: checkpointer continuous flushing - Mailing list pgsql-hackers

From Fabien COELHO
Subject Re: checkpointer continuous flushing
Date
Msg-id alpine.DEB.2.10.1601071126020.5278@sto
Whole thread Raw
In response to Re: checkpointer continuous flushing  (Fabien COELHO <coelho@cri.ensmp.fr>)
Responses Re: checkpointer continuous flushing  (Andres Freund <andres@anarazel.de>)
List pgsql-hackers
<Ooops, wrong from address, resent, sorry for the noise>

Hello Andres,

>>> Although I disagree with some aspects of Andres patch, I'm not a
>>> committer and I'm tired of arguing. I'm just planing to do minor changes
>>> to Andres version to fix a potential issue if the file is closed which
>>> flushing is in progress, but that will not change the overall shape of 
>>> it.
> 
> Are you working on that aspect?

I read your patch and I know what I want to try to have a small and simple 
fix. I must admit that I have not really understood in which condition the 
checkpointer would decide to close a file, but that does not mean that the 
potential issue should not be addressed.

Also, I gave some thoughts about what should be done for bgwriter random IOs. 
The idea is to implement some per-file sorting there and then do some LRU/LFU 
combing. It would not interact much with the checkpointer, so for me the two 
issues should be kept separate and this should not preclude changing the 
checkpointer, esp. given the significant performance benefit of the patch.

However, all this is still in my stack of things to do, and I had not much 
time in the Fall for that. I may have more time in the coming weeks. I'm fine 
if things are updated and performance figures are collected in between, I'll 
take it from where it is when I have time, if something remains to be done.

-- 
Fabien.



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