From muir@idiom.com  Sat Jan 14 03:40:49 1995
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Date: Sat, 14 Jan 1995 03:40:40 -0800
From: David Muir Sharnoff <muir@idiom.com>
Reply-To: muir@idiom.com
To: FreeBSD-gnats-submit@freebsd.org
Subject: disk transfer rates reported by systat :iostat are too high
X-Send-Pr-Version: 3.2

>Number:         116
>Category:       bin
>Synopsis:       disk transfer rates reported by systat :iostat are too high
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-bugs
>State:          closed
>Quarter:
>Keywords:
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Sat Jan 14 03:50:01 1995
>Closed-Date:    Sat Apr 13 21:42:20 PDT 1996
>Last-Modified:  Sat Apr 13 21:42:48 PDT 1996
>Originator:     David Muir Sharnoff
>Release:        FreeBSD 2.0-RELEASE i386
>Organization:
Idiom Consulting
>Environment:

	I have a fast disk.  It can maybe do 13000 bps.

>Description:

	In preparing my last bug report, I captured the following screen:

                  /0   /5   /10  /15  /20  /25  /30  /35  /40  /45  /50
        fd0   bps|XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX2919.5
              tps|XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
        fd1   bps|
              tps|
        sd0   bps|XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX93745.0
              tps|XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
        cd0   bps|
              tps|

	93745 is too high to be believed.  The best my disk should
	be able to do is around 13000bps.  (I suppose it could
	burst higher due to its caching controller, but 93745 bps
	is not to be believed)

>How-To-Repeat:

	watch systat :iostat, see if you believe it.

	I did the following to generate the numbers above:

	idiom# dd if=/dev/rsd0a of=/dev/null bs=1000k
	24+1 records in
	24+1 records out
	25165824 bytes transferred in 4 secs (6291456 bytes/sec)

	Oh!  Wait, perhaps the number is bps but total blocks transfered
	in since the last update period.  No, that doesnt' explain it because
	I only transfered around 13000 blocks during that period.  No, wait,
	does /dev/null count?

	Nope, it doesn't.

>Fix:
>Release-Note:
>Audit-Trail:
State-Changed-From-To: open->closed 
State-Changed-By: scrappy 
State-Changed-When: Sat Apr 13 21:42:20 PDT 1996 
State-Changed-Why:  
Originator reports that numbers agree now with what is expected 
>Unformatted:


