On 11/7/2012 6:37 AM, Devrim GÜNDÜZ wrote:
HT should be good for file servers, or say many of the app servers, or
small web/mail servers. PostgreSQL relies on the CPU power, and since
the HT CPUs don't have the same power as the original CPU, when OS
submits a job to that particular HTed CPU, query will run significantly
slow. To avoid issues, I would suggest you to turn HT off on all
PostgreSQL servers. If you can throw some more money, another 6-core CPU
would give more benefit.
I realize this is the "received knowledge" but it is not supported by
the evidence before me (which is that I get nearly 2x the throughput
from pgbench using nthreads == nhtcores vs nthreads == nfullcores).
Intel's latest HT implementation seems to suffer less from the kinds of
resource sharing contention issues seen in older generations.
Once I have the machine's full memory installed I'll run pgbench with HT
disabled in the BIOS and post the results.
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