Scott, are you really moving that much data through memory, 70-80GB/sec is the limit of the new intel 7500 series in a best case scenario. - John -----Original Message----- From: pgsql-performance-owner@xxxxxxxxxxxxxx [mailto:pgsql-performance-owner@xxxxxxxxxxxxxx] On Behalf Of Scott Marlowe Sent: 16 February 2011 15:43 To: Marti Raudsepp Cc: Thomas Pöhler; pgsql-performance@xxxxxxxxxxxxxx; Felix Feinhals; Verteiler_A-Team; Björn Metzdorf Subject: Re: high user cpu, massive SELECTs, no io waiting problem On Wed, Feb 16, 2011 at 6:44 AM, Marti Raudsepp <marti@xxxxxxxxx> wrote: > On Tue, Feb 15, 2011 at 20:01, Scott Marlowe <scott.marlowe@xxxxxxxxx> wrote: >> run htop and look for red. if youi've got lots of red bar on each CPU >> but no io wait then it's waiting for memory access. > > I don't think this is true. AFAICT the red bar refers to "system > time", time that's spent in the kernel -- either in syscalls or kernel > background threads. My point being that if you've got a lot of RED it'll be the OS waiting for memory access. Trust me, when we start to hit our memory bandwidth (in the 70 to 80 GB/s range) we start to get more and more red and more and more kernel wait time. -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance This communication is for informational purposes only. It is not intended as an offer or solicitation for the purchase or sale of any financial instrument or as an official confirmation of any transaction. All market prices, data and other information are not warranted as to completeness or accuracy and are subject to change without notice. Any comments or statements made herein do not necessarily reflect those of JPMorgan Chase & Co., its subsidiaries and affiliates. This transmission may contain information that is privileged, confidential, legally privileged, and/or exempt from disclosure under applicable law. If you are not the intended recipient, you are hereby notified that any disclosure, copying, distribution, or use of the information contained herein (including any reliance thereon) is STRICTLY PROHIBITED. Although this transmission and any attachments are believed to be free of any virus or other defect that might affect any computer system into which it is received and opened, it is the responsibility of the recipient to ensure that it is virus free and no responsibility is accepted by JPMorgan Chase & Co., its subsidiaries and affiliates, as applicable, for any loss or damage arising in any way from its use. If you received this transmission in error, please immediately contact the sender and destroy the material in its entirety, whether in electronic or hard copy format. Thank you. Please refer to http://www.jpmorgan.com/pages/disclosures for disclosures relating to European legal entities. -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
