-hackers,
While updating my Postgres performance curriculum I was doing some
testing with effective_io_concurrency and I may have found a regression.
I am aware that the parameter only works under certain conditions.
However, what I appear to have found is that if it is set to anything
but 0, it is a regression for (at least benchmarksql tpc-c) workloads.
See here:
Testing with the TPC style benchmark shows that on local systems,
setting this between 0 – 48 keeps the TPS within noise level. However,
testing also shows that on cloud systems such as Google Cloud Compute
setting this setting to anything greater than 0 results in an
approximately 10% performance degradation on TPS:
Local/GCE effective_io_concurrency TPS
GCE OFF 47951
8 43098
1 43233
LOCAL 0 9939
4 9960
16 9955
48 9958
I was able to produce these results pretty consistently. I wonder if any
has seen this on EBS? GCE instance is 16CPU, 59GB memory, 240MB
Sustained rate SSD with 15k IOPS.
Thanks,
JD
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