> 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 -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
