Messages in this thread | | | Date | Thu, 24 Mar 2005 23:09:17 -0500 | From | Jeff Garzik <> | Subject | Re: Promise SX8 performance issues and CARM_MAX_Q |
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Matthew Collins wrote: > Jeff Garzik wrote: > >> Bernard Blackham wrote: >> >>> Hi, >>> >>> Playing with a recently acquired Promise SX8 card, we've found >>> similar performance results to Matt's post to lkml a few months back >>> at http://marc.theaimsgroup.com/?l=linux-kernel&m=110175890323356&w=2 >>> >>> It appears that the driver is only submitting one command at a time >>> per port, which is at least one cause of the slowdowns. By raising >>> CARM_MAX_Q from 1 to 3 in drivers/block/sx8.c (it was 3 in an >>> earlier pre-merge incarnation of carmel.c), we're getting very >>> notable speed improvements, with no side effects just yet. >>> >>> Knowing very little about what this change has actually done, I've a >>> few questions: >>> - Should this be considered dangerous? >>> - Why was it taken from 3 to 1? >>> - Is CARM_MAX_Q a number defined (or limited) by the hardware? >> >> >> >> In multi-port stress tests, we couldn't get SX8 to function reliably >> without locking up or corrupting data, with more than one outstanding >> command. >> >> Maybe a new firmware has solved this by now. >> >> Jeff >> >> >> > Indeed there does seem to be new firmware out as of 2/23/05. I ran my > tests with the 9/10/04 firmware but I did not adjust the CARM_MAX_Q > value. Do either of you happen to know what firmware revisions you > tested under? > > I've put the machine with the SX8 controller into production despite the > performance issues so I'm not going to be of any use for testing > revisions to the driver :(
The driver was developed on a pre-production board, so its entirely possible Promise fixed this issue.
The driver should be solid for _at least_ CARM_MAX_Q==31, presuming that the firmware doesn't choke.
Anybody willing to (a) change CARM_MAX_Q (b) use the latest firmware (c) stress the card with fsx, badblocks, iozone, and other tools on -multiple ports- simultaneously.
?
Jeff
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