On 09/26/2016 07:16 PM, Tomas Vondra wrote:

The averages (over the 10 runs, 5 minute each) look like this:

 3.2.80                 1      8     16     32     64    128    192
--------------------------------------------------------------------
 granular-locking    1567  12146  26341  44188  43263  49590  15042
 no-content-lock     1567  12180  25549  43787  43675  51800  16831
 group-update        1550  12018  26121  44451  42734  51455  15504
 master              1566  12057  25457  42299  42513  42562  10462

 4.5.5                  1      8     16     32     64    128    192
--------------------------------------------------------------------
 granular-locking    3018  19031  27394  29222  32032  34249  36191
 no-content-lock     2988  18871  27384  29260  32120  34456  36216
 group-update        2960  18848  26870  29025  32078  34259  35900
 master              2984  18917  26430  29065  32119  33924  35897

That is:

(1) The 3.2.80 performs a bit better than before, particularly for 128
and 256 clients - I'm not sure if it's thanks to the reboots or so.

(2) 4.5.5 performs measurably worse for >= 32 clients (by ~30%). That's
a pretty significant regression, on a fairly common workload.


FWIW, now that I think about this, the regression is roughly in line with my findings presented in my recent blog post:

    http://blog.2ndquadrant.com/postgresql-vs-kernel-versions/

Those numbers were collected on a much smaller machine (2/4 cores only), which might be why the difference observed on 32-core machine is much more significant.

regards

--
Tomas Vondra                  http://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services


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