Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3

> On Wed, Aug 20, 2014 at 12:13:50PM -0700, Josh Berkus wrote:
>> On a read-write test, it's 10% faster with HT off as well.
>>
>> Further, from their production machine we've seen that having HT on
>> causes the machine to slow down by 5X whenever you get more than 40
>> cores (as in 100% of real cores or 50% of HT cores) worth of activity.
>>
>> So we're definitely back to "If you're using PostgreSQL, turn off
>> Hyperthreading".
>
> Not sure how you can make such a blanket statement when so many people
> have tested and shown the benefits of hyper-threading. I am also
> unclear exactly what you tested, as I didn't see it mentioned in the
> email --- CPU type, CPU count, and operating system would be the minimal
> information required.

HT off is common knowledge for better benchmarking result, at least
for me. I've never seen better result with HT on, except POWER.

Best regards,
--
Tatsuo Ishii
SRA OSS, Inc. Japan
English: http://www.sraoss.co.jp/index_en.php
Japanese:http://www.sraoss.co.jp