RE: [ANNOUNCE]: megaraid driver version 2.20.0.1

[James Bottomley <James.Bottomley@SteelEye.com>]

On Wed, 2004-07-21 at 08:48, Mukker, Atul wrote:
> > The philosophy for scsi drivers for a while has been to 
> > remove internal
> > queueing, which is why yours attracted my attention, so the question I
> > was asking is can you use these APIs instead of having to 
> > maintain this
> > internal queue?
> The internal pending queue is fed not only from the mid-layer packets but
> also the packets from the management module and (forthcoming) sysfs module.
> Both of these modules rely on the fact that the commands issued by them
> would be issued sooner or later.

Hmm, well, in order to re-use the block layer queueing, you can wrap
these up into special requests and queue them as well.  The actual SCSI
implementation does do a head of queue add, so any request so queued is
the first to be pulled off again and executed

> In addition, in certain situations (logical drive deletion) driver has to
> stop sending commands to the FW before these operations can be initiated.
> This is also implemented using the pending queue mechanism. Although would
> be minor change to move over to scsi_block_requests and scsi_unblock_request
> to achieve this.
> 
> This is not to say that I am reluctant to implement SCSI_MLQUEUE_HOST_BUSY,
> but just a precursor where additional impacts would be so that reviewers can
> focus on those areas as well.

Well, OK, just do the changes to get rid of yield, and we can look at
fixing the queuing in tree.

James