Re: XLogInsert

On Wednesday 16 December 2009 20:07:07 Gurjeet Singh wrote:
> 2009/12/15 Greg Smith <greg(at)2ndquadrant(dot)com>
>
> > Jaime Casanova wrote:
> >> So in this extreme case avg tps is just 6 transactions better
> >
> > Great job trying to find the spot where the code worked better. I'm not
> > so sure I trust pgbench results where the TPS was so low though. Which
> > leads us right back to exactly how Jeff measured his original results.
> >
> > As I said already, I think we need more insight into Jeff's performance
> > report, a way to replicate that test, to look a bit at the latency as
> > reported by the updated LWLock patch that Pierre submitted. Tweaking
> > your test to give more useful results is a nice second opinion on top of
> > that. But we're out of time for now, so this patch is getting returned
> > with feedback. I encourage Jeff to resubmit the same patch or a better
> > one with a little more data on performance measurements to our final 8.5
> > CommitFest in hopes we can confirm this an improvement worth committing.
>
> Last week I worked on a FUSE based filesystem, which I call BlackholeFS.
> Its similar to /dev/null, but for directories. Basically it simply returns
> success for all the writes, but doesn't do any writes on the files under
> it.
I doubt that it will be faster than a tmpfs - the additional context switches
et al probably will hurt already.
If you constrain the checkpoint_segments to something sensible it shouldnt use
too much memory.

Andres