RE: 7.0.3(nofsync) vs 7.1 - Mailing list pgsql-hackers

From Mikheev, Vadim
Subject RE: 7.0.3(nofsync) vs 7.1
Date
Msg-id 8F4C99C66D04D4118F580090272A7A234D31F6@sectorbase1.sectorbase.com
Whole thread Raw
In response to 7.0.3(nofsync) vs 7.1  ("Mikheev, Vadim" <vmikheev@SECTORBASE.COM>)
List pgsql-hackers
> >> What is the default commit delay now?
> 
> > As before 5 * 10^(-6) sec - pretty the same as sleep(0) -:)
> > Seems CommitDelay is not very useful parameter now - XLogFlush
> > logic and fsync time add some delay.
> 
> There was a thread recently about smarter ways to handle shared fsync
> of the log --- IIRC, we talked about self-tuning commit delay,
> releasing waiting processes as soon as someone else had fsync'd, etc.
> Looks like none of those ideas are in the code now.  Did you not like 
> any of those ideas, or just no time to work on it yet?

We're in beta - it's better to test WAL to find/fix bugs than make
further improvements.

Also, I've run test with 100 clients inserting records into 100 tables
(to minimize contentions) - 915 tps with fsync and 1190 tps without fsync.
So, we do ~ 18 commits per fsync now and probably we'll be able to
increase commit performance by ~ 30%, no more.

Vadim


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