Re: Problem with aacraid driver in 2.5.63-bk-latest
Mark Haverkamp <[email protected]>
| Newsgroups | gmane.linux.scsi,gmane.linux.kernel,gmane.linux.drivers.aacraid.devel |
|---|---|
| Message-ID | <[email protected]> |
On Thu, 2003-03-13 at 15:17, Doug Ledford wrote: > Mark Haverkamp wrote: > > > Does the cmd_per_lun element of the Scsi_Host_Template structure serve > > more than one purpose? > > Only when inappropriately abused by LLDD authors. The cmd_per_lun value > is suppossed to be for untagged devices only! If you have a tape drive > that doesn't support tagged commands but you want to be able to > internally have the next command queued up and ready to go when the > current command completes (in order to keep it streaming better), then > you can set cmd_per_lun to 2 and you will get two outstanding commands > for this device at a time. I used that so that in my interrupt handler > I could send the next command to the device before I passed the > completed command up to the SCSI layer. > > > In scsi_alloc_sdev it is passed into > > scsi_adjust_queue_depth. In the aacraid case this is 512. Later the > > aacraid driver (in aac_slave_configure) sets the queue depth to either > > 128 for tagged or 1 if not. > > That's where you are suppossed to set the queue depth on tagged devices. Then it sounds like the aacraid driver could set cmd_per_lun to a small number like one since the real queue depth will be set later in aac_slave_configure. Mark. -- Mark Haverkamp <[email protected]> - To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html