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Date:      Tue, 04 Jul 2000 04:08:47 -0700
From:      Mike Smith <msmith@freebsd.org>
To:        "Kenneth D. Merry" <ken@kdm.org>
Cc:        David Gilbert <dgilbert@velocet.ca>, Kent Stewart <kstewart@3-cities.com>, freebsd-stable@FreeBSD.ORG
Subject:   Re: Dump takes ages on SCSI. (several times faster on IDE) 
Message-ID:  <200007041108.EAA02369@mass.osd.bsdi.com>
In-Reply-To: Your message of "Sun, 02 Jul 2000 23:55:24 MDT." <20000702235524.A19820@panzer.kdm.org> 

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> When the da(4) driver does a dump, it uses the CAM transport layer's polled
> completion/action facility, xpt_polled_action().
> 
> It looks like there is a substantial delay (1ms) in that routine between
> poll intervals.

That would still allow 4MB/sec (1 page per I/O) - I think there's more to 
it than just that.

-- 
... every activity meets with opposition, everyone who acts has his
rivals and unfortunately opponents also.  But not because people want
to be opponents, rather because the taks and relationships force
people to take different points of view.  [Dr. Fritz Todt]




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