[7686] in linux-scsi channel archive
Re: How do I invoke a re-probe from kernel space?
daemon@ATHENA.MIT.EDU (Eric Youngdale)
Mon Dec 13 13:03:18 1999
Message-ID: <001e01bf4589$80be1440$940310ac@fairfax.datafocus.com>
From: "Eric Youngdale" <eric@andante.org>
To: <mkwasigr@INTERCOPE.COM>
Cc: <linux-scsi@vger.rutgers.edu>
Date: Mon, 13 Dec 1999 11:45:37 -0500
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----- Original Message -----
From: <mkwasigr@INTERCOPE.COM>
To: Eric Youngdale <eric@andante.org>
Cc: <linux-scsi@vger.rutgers.edu>
Sent: Monday, December 13, 1999 10:57 AM
Subject: Re: How do I invoke a re-probe from kernel space?
> Hi Eric,
>
> you wrote:
> > My guess is that the problem is that when you do an
> > add-single-device that it calls down to the low-level driver to select
> the
> > queue depth again. The problem is (as the comment describes) that the
> > low-level drivers may not expect being called to do this task a second
> > time.
>
> So, it appears to me that
> a) the problem is in the aic7xxx low-level driver.
Not really. The function to set the queue depth was never designed for
this purpose. Thus the driver would have reason to be surprised by being
called a second time. In such a case there is kind of a grey area as to
where the problem might be.
Realistically, I suspect that the easiest fix is to get the aic7xxx
driver to tolerate being called again, assuming that this is where the
problem actually lies.
> b) the problem will not be cured in the next 2.3 releases.
Correct.
> Allow me to repeat my previous questions:
> 1. Has anybody else experienced this loss of tagged command
> queueing on "add-single-device"?
> 2. Is anybody working on a solution, especially for the aic7xxx driver?
>
> The "add-single-device" is **VERY** handy. I want to use it to be able to
> switch my SCSI DAT tape on and off without the need to reboot. But if I
> lose
> the queue depth for my SCSI disks, I fear the perfomance penalty... :-(
>
>
> Mit freundlichen Gruessen / best regards
>
> Michael Kwasigroch
> FaxPlus/Open Development
> ________________________________________
>
> eMail: mkwasigr@intercope.com
>
> INTERCOPE GmbH, Hamburg, Bebelallee 72
>
>
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