Heikki Linnakangas wrote:
> Alvaro Herrera wrote:
> > Heikki Linnakangas wrote:
> > 
> >> I ran two 24h test runs with DBT-2, one with the patch and one without. 
> >> To get comparable, predictable results, I turned autovacuum off and run 
> >> a manual vacuum in a loop on the stock-table alone.
> >>
> >> As expected, the steady-state of the stock table is smaller with the 
> >> patch. But only by ~2%, that's slightly less than I expected.
> >>
> >> But what surprises me is that response times went up a with the patch. I 
> >> don't know why.
> > 
> > Maybe because of increased contention of ProcArrayLock?  (I assume you
> > are using that, althought I haven't seen the patch)
> I am, but I doubt that's it. The response times are dominated by I/O, so 
> any increase in lock contention would hardly show up. And the patch is 
> only adding one GetOldestXmin call every 1000 scanned pages, which is 
> nothing compared to the thousands of GetSnapshot calls the normal 
> transactions are issuing per minute.
> The patch must have changed the I/O pattern in some subtle way.

So are you stopping work on the patch?  I assume so.

  Bruce Momjian  <[EMAIL PROTECTED]>          http://momjian.us
  EnterpriseDB                               http://www.enterprisedb.com

  + If your life is a hard drive, Christ can be your backup. +

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