Re: Patch: Write Amplification Reduction Method (WARM)

On Tue, Mar 14, 2017 at 7:19 PM, Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>
wrote:

> Pavan Deolasee wrote:
>
> > BTW I wanted to share some more numbers from a recent performance test. I
> > thought it's important because the latest patch has fully functional
> chain
> > conversion code as well as all WAL-logging related pieces are in place
> > too. I ran these tests on a box borrowed from Tomas (thanks!). This has
> > 64GB RAM and 350GB SSD with 1GB on-board RAM. I used the same test setup
> > that I used for the first test results reported on this thread i.e. a
> > modified pgbench_accounts table with additional columns and additional
> > indexes (one index on abalance so that every UPDATE is a potential WARM
> > update).
> >
> > In a test where table + indexes exceeds RAM, running for 8hrs and
> > auto-vacuum parameters set such that we get 2-3 autovacuums on the table
> > during the test, we see WARM delivering more than 100% TPS as compared to
> > master. In this graph, I've plotted a moving average of TPS and the
> spikes
> > that we see coincides with the checkpoints (checkpoint_timeout is set to
> > 20mins and max_wal_size large enough to avoid any xlog-based
> checkpoints).
> > The spikes are more prominent on WARM but I guess that's purely because
> it
> > delivers much higher TPS. I haven't shown here but I see WARM updates
> close
> > to 65-70% of the total updates. Also there is significant reduction in
> WAL
> > generated per txn.
>
> Impressive results. Labels on axes would improve readability of the chart
> :-)
>
>
Sorry about that. I was desperately searching for Undo button after hitting
"send" for the very same reason :-) Looks like I used gnuplot after a few
years.

Just to make it clear, the X-axis is duration of tests in seconds and
Y-axis is 450s moving average of TPS. BTW 450 is no magic figure. I
collected stats every 15s and took a moving average of last 30 samples.

Thanks,
Pavan

--
Pavan Deolasee http://www.2ndQuadrant.com/
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