Typically my problem is that the large queries are simply CPU bound.. do you have a sar/top output that you see. I'm currently setting up two FusionIO DUO @640GB in a lvm stripe to do some testing with, I will publish the results after I'm done. If anyone has some tests/suggestions they would like to see done please let me know. - John -----Original Message----- From: pgsql-performance-owner@xxxxxxxxxxxxxx [mailto:pgsql-performance-owner@xxxxxxxxxxxxxx] On Behalf Of Przemek Wozniak Sent: Thursday, December 23, 2010 11:38 AM To: pgsql-performance@xxxxxxxxxxxxxx Subject: concurrent IO in postgres? When testing the IO performance of ioSAN storage device from FusionIO (650GB MLC version) one of the things I tried is a set of IO intensive operations in Postgres: bulk data loads, updates, and queries calling for random IO. So far I cannot make Postgres take advantage of this tremendous IO capacity. I can squeeze a factor of a few here and there when caching cannot be utilized, but this hardware can do a lot more. Low level testing with fio shows on average x10 speedups over disk for sequential IO and x500-800 for random IO. With enough threads I can get IOPS in the 100-200K range and 1-1.5GB/s bandwidth, basically what's advertised. But not with Postgres. Is this because the Postgres backend is essentially single threaded and in general does not perform asynchronous IO, or I'm missing something? I found out that the effective_io_concurrency parameter only takes effect for bitmap index scans. Also, is there any work going on to allow concurrent IO in the backend and adapt Postgres to the capabilities of Flash? Will appreciate any comments, experiences, etc. Przemek Wozniak -- 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
