lkml.org 
[lkml]   [2002]   [Mar]   [1]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: queue_nr_requests needs to be selective
Jeff V. Merkey [jmerkey@vger.timpanogas.org] wrote:
>
> ..snip..
>
> What is really needed here is to allow queue_nr_requests to be
> configurable on a per adapter/device basis for these high end
> raid cards like 3Ware since in a RAID 0 configuration, 8 drives
> are in essence a terabyte (1.3 terrabytes in our configuration)
> and each adapter is showing up as a 1.3 TB device. 64/128
> requests are simply not enough to get the full spectrum of
> performance atainable with these cards.
>
Not having direct experience on this card it appears that increasing the
queue_nr_requests number will not allow you to have more ios in flight.

Unless I am reading the driver wrong you will be limited to
TW_MAX_CMDS_PER_LUN (15). This value is used by scsi_build_commandblocks
to allocate scsi commands for your scsi_device. This driver does not provide
a select_queue_depths function which allows for increase to the default
template value.

Could it be that the experimentation of increasing this number has
allowed for better merging.

-Mike
--
Michael Anderson
andmike@us.ibm.com

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 13:24    [W:0.319 / U:0.240 seconds]
©2003-2014 Jasper Spaans. Advertise on this site