[lkml]   [2002]   [Mar]   [1]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: queue_nr_requests needs to be selective
Jeff V. Merkey [] 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.

Michael Anderson

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

 \ /
  Last update: 2005-03-22 13:24    [from the cache]
©2003-2014 Jasper Spaans. hosted at Digital Ocean