Re: Scaling shared buffer eviction - Mailing list pgsql-hackers

On 05/09/14 23:50, Amit Kapila wrote:
> On Fri, Sep 5, 2014 at 8:42 AM, Mark Kirkwood
> <mark.kirkwood@catalyst.net.nz <mailto:mark.kirkwood@catalyst.net.nz>>
> wrote:
>  >
>  > On 04/09/14 14:42, Amit Kapila wrote:
>  >>
>  >> On Thu, Sep 4, 2014 at 8:00 AM, Mark Kirkwood
> <mark.kirkwood@catalyst.net.nz <mailto:mark.kirkwood@catalyst.net.nz>>
>  >> wrote:
>  >>>
>  >>>
>  >>>
>  >>> Hi Amit,
>  >>>
>  >>> Results look pretty good. Does it help in the read-write case too?
>  >>
>  >>
>  >> Last time I ran the tpc-b test of pgbench (results of which are
>  >> posted earlier in this thread), there doesn't seem to be any major
>  >> gain for that, however for cases where read is predominant, you
>  >> might see better gains.
>  >>
>  >> I am again planing to take that data in next few days.
>  >>
>  >
>  > FWIW below are some test results on the 60 core beast with this patch
> applied to 9.4. I'll need to do more runs to iron out the variation,
>  > but it looks like the patch helps the standard (write heavy) pgbench
> workload a little, and clearly helps the read only case.
>  >
>
> Thanks for doing the test.  I think if possible you can take
> the performance data with higher scale factor (4000) as it
> seems your m/c has 1TB of RAM.  You might want to use
> latest patch I have posted today.
>

Here's some fairly typical data from read-write and read-only runs at 
scale 4000 for 9.4 beta2 with and without the v7 patch (below). I'm not 
seeing much variation between repeated read-write runs with the same 
config (which is nice - sleep 30 and explicit checkpoint call between 
each one seem to help there).

Interestingly, I note anecdotally that (unpatched) 9.4 beta2 seems to be 
better at higher client counts than beta1 was...

In terms of the effect of the patch - looks pretty similar to the scale 
2000 results for read-write, but read-only is a different and more 
interesting story - unpatched 9.4 is noticeably impacted in the higher 
client counts, whereas the patched version scales as well (or even 
better perhaps) than in the scale 2000 case.

read write (600s)

Clients  | tps    | tps (unpatched)
---------+--------+----------------  6      |   9395 |   9334  12     |  16605 |  16525  24     |  24634 |  24910  48
 |  32170 |  31275  96     |  35675 |  36533 192     |  35579 |  31137 384     |  30528 |  28308
 


read only (300s)

Clients  | tps    | tps (unpatched)
---------+--------+----------------  6      |  35743 |   35362  12     | 111019 |  106579  24     | 199746 |  160305
48    | 327026 |  198407  96     | 379184 |  171863 192     | 356623 |  152224 384     | 340878 |  128308
 


regards

Mark