Re: effective_io_concurrency

On Thu, Aug 30, 2012 at 1:25 PM, Peter Geoghegan <peter@2ndquadrant.com> wrote:

> Just how helpful is effective_io_concurrency? Did someone produce a
> benchmark at some point?

Attached is a benchmark I put together a while ago.

I don't know how close to "real world" it might be.  I haven't seen it
in the wild, but I'm anticipating I will see something like it soon.

The benefit is of course reduced if you were to apply high levels of
-c $clients, but cases where -c 1 are frequent in data mining and
such.

Obviously it would be better to cluster the giant table on "abalance",
but that might be hard to do and then hard to maintain.

Size of generated database is about 70GB.

Server had 16GB of RAM.  It is a virtual server, and I don't know the
real hardware, but am told it has 8 spindles.
(if the range used in the query is increased from +100 to +1000, even
more speed up is available)

effective_io_concurrency	tps
0	2.06273064
1	2.1693092
2	4.11726948
3	5.90785352
4	6.65748384
5	7.58297556
6	8.36130404
7	8.86561116
8	9.2673546
9	9.57076168
10	9.8558758
11	10.11641752
12	10.316673
13	10.46953468
14	10.65962516
15	10.76328636
16	10.86442376
17	10.96362168
18	11.04371008
19	11.19470171
20	11.30110867
21	11.39553967
22	11.45420263
23	11.54764725
24	11.61949146
25	11.65659225
26	11.68992392
27	11.75944667
28	11.7456135
29	11.80111779
30	11.72897188
31	11.7210945
32	11.73292504
33	11.734458
34	11.75195196
35	11.79079175
36	11.73687979
37	11.79583758
38	11.75879063
39	11.77868596
40	11.74685896
41	11.76294508
42	11.7213265
43	11.68458158
44	11.71036729
45	11.72728229
46	11.72063796
47	11.80322429
48	11.83563058
49	11.81916996
50	11.73395892

Cheers,

Jeff