From owner-freebsd-hackers  Wed May 22  9:14:27 2002
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Date: Wed, 22 May 2002 12:14:20 -0400 (EDT)
From: Zhihui Zhang <zzhang@cs.binghamton.edu>
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To: freebsd-hackers@freebsd.org
Subject: kernel I/O timing statistics
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I have a need to record the total physical times spent on I/O requests
during some period.  My basic idea is to record the start time when the
request is issued somewhere in a disk driver and the finish time somewhere
in an interrupt routine. Can any one please tell me where are the right
places to insert these hooks to collect these timing information for SCSI
and IDE disks? I have only a little information about the driver structure
in FreeBSD. Maybe this is not a good idea.

Thanks for any enlightenment.

-Zhihui


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