Received: from malur.postgresql.org ([217.196.149.56]) by arkaria.postgresql.org with esmtp (Exim 4.80) (envelope-from ) id 1XM67H-0000hO-9J for pgsql-performance@arkaria.postgresql.org; Tue, 26 Aug 2014 02:04:11 +0000 Received: from localhost ([127.0.0.1] helo=postgresql.org) by malur.postgresql.org with smtp (Exim 4.80) (envelope-from ) id 1XM67G-0001qD-AK for pgsql-performance@arkaria.postgresql.org; Tue, 26 Aug 2014 02:04:10 +0000 Received: from makus.postgresql.org ([2001:4800:1501:1::229]) by malur.postgresql.org with esmtps (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1XM67E-0001q4-2S for pgsql-performance@postgresql.org; Tue, 26 Aug 2014 02:04:08 +0000 Received: from mail.catalyst.net.nz ([2404:130:0:10::40:0]) by makus.postgresql.org with esmtp (Exim 4.80) (envelope-from ) id 1XM675-00036q-ND for pgsql-performance@postgresql.org; Tue, 26 Aug 2014 02:04:06 +0000 Received: from localhost (localhost [127.0.0.1]) by mail.catalyst.net.nz (Postfix) with ESMTP id 157FA32705; Tue, 26 Aug 2014 14:03:54 +1200 (NZST) X-Virus-Scanned: Debian amavisd-new at catalyst.net.nz Received: from mail.catalyst.net.nz ([127.0.0.1]) by localhost (bertrand.catalyst.net.nz [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id z-tnBZZYgfEz; Tue, 26 Aug 2014 14:03:53 +1200 (NZST) Received: from [IPv6:2404:130:0:1000:a4fc:f789:d6fa:5f91] (unknown [IPv6:2404:130:0:1000:a4fc:f789:d6fa:5f91]) (Authenticated sender: mark.kirkwood) by mail.catalyst.net.nz (Postfix) with ESMTPSA id 3662D31E01; Tue, 26 Aug 2014 14:03:53 +1200 (NZST) Message-ID: <53FBEB09.1050706@catalyst.net.nz> Date: Tue, 26 Aug 2014 14:03:53 +1200 From: Mark Kirkwood User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.0 MIME-Version: 1.0 To: Josh Berkus , Andres Freund CC: Bruce Momjian , pgsql-performance@postgresql.org, "Graeme B. Bell" Subject: Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 References: <53ACB190.2030206@catalyst.net.nz> <53ECFD75.3060408@agliodbs.com> <53ED371D.109@catalyst.net.nz> <53F4F36E.6050003@agliodbs.com> <20140821024036.GB26706@momjian.us> <53F65E62.3020909@agliodbs.com> <20140822140223.GP17406@alap3.anarazel.de> <53FBB527.9030007@agliodbs.com> In-Reply-To: <53FBB527.9030007@agliodbs.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit X-Pg-Spam-Score: -1.9 (-) List-Archive: List-Help: List-ID: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: X-Mailing-List: pgsql-performance Precedence: bulk Sender: pgsql-performance-owner@postgresql.org On 26/08/14 10:13, Josh Berkus wrote: > On 08/22/2014 07:02 AM, Andres Freund wrote: >> On 2014-08-21 14:02:26 -0700, Josh Berkus wrote: >>> On 08/20/2014 07:40 PM, Bruce Momjian wrote: >>>> Not sure how you can make such a blanket statement when so many people >>>> have tested and shown the benefits of hyper-threading. >>> >>> Actually, I don't know that anyone has posted the benefits of HT. >>> Link? >> >> There's definitely cases where it can help. But it's highly workload >> *and* hardware dependent. > > The only cases I've seen where HT can be beneficial is when you have > large numbers of idle connections. Then the idle connections can be > "parked" on the HT virtual cores. However, even in this case I haven't > seen a head-to-head performance comparison. > I recall HT beneficial on a single socket (i3 or i7), using pgbench as the measuring tool. However I didn't save the results at the time. I've just got some new ssd's to play with so might run some pgbench tests on my home machine (Haswell i7) with HT on and off. Regards Mark -- Sent via pgsql-performance mailing list (pgsql-performance@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance