[no subject]

> > Seriously, I found that over a T1, ssh  would take up a couple of percent
> > of the CPU.  (This was a couple of years ago--it should be less with a
> > modern CPU.)  That does make the numbers you're getting a little higher
> > than I would expect.  At 1% of a CPU for T1 speed, I'd expect 10% at
> > 10-baseT and 100% for 100-baseT.  Seems like our numbers disagree by a
> > factor of 10.
>
> I wouldn't think the cpu usage would vary with the size of the pipe, if
> it did, I'd expect higher usage with a bigger pipe.  With the smaller
> pipe, you'd have it waiting on i/o.

Exactly what I was saying.  When you aren't I/O bound you become CPU bound.  A 
T1 is about 1.5 Mbps, so you end up IO bound.  With a fat pipe like 100 Mbps 
your CPU becomes a critical factor.  

> I find the cpu usage to be much higher than 1%.  When transfering a file
> 125M file from my athlon 2400 to my PIV 2400 the cpu usage on the
> sending machine was at 35-40% for ssh.  It was comparable on the
> receiving machine.  When sending the same file from the Athlon to a PII
> 350 the cpu usage was hovering around 80%.

Sounds like you are doing a fair amount of waiting for disk, too--maybe around 
40-60%.  Does the slow system have slower drives, too?  

I wonder how much readahead there is in ssh.  Does it read a block, encode a 
block, send a block sequentially, or is it threaded so that it has a thread 
reading and a thread encoding and a thread sending.  If the former, then 
there is some room for improvement.

> So our numbers are far different.

Not so different.  I was on a thin pipe about 70 times narrower than yours and 
got 1-2% cpu.  The drives were fast as it was a server system--maybe raid 
scsi.  If I were on your network, I'd expect 100-140% CPU utilization, were 
it not for the disk I/O.  If I spent 50% of the time waiting for slow drives, 
then a CPU utilization of under 50% would be expected.

Michael


</pre>
<!--X-Body-of-Message-End-->
<!--X-MsgBody-End-->
<!--X-Follow-Ups-->
<hr>
<!--X-Follow-Ups-End-->
<!--X-References-->
<ul><li><strong>References</strong>:
<ul>
<li><strong><a name="00663" href="msg00663.html">[ale] sshd resource intensive??</a></strong>
<ul><li><em>From:</em> esoteric at 3times25.net (Geoffrey)</li></ul></li>
<li><strong><a name="00698" href="msg00698.html">[ale] sshd resource intensive??</a></strong>
<ul><li><em>From:</em> mhirsch at nubridges.com (Michael D. Hirsch)</li></ul></li>
<li><strong><a name="00702" href="msg00702.html">[ale] sshd resource intensive??</a></strong>
<ul><li><em>From:</em> esoteric at 3times25.net (Geoffrey)</li></ul></li>
</ul></li></ul>
<!--X-References-End-->
<!--X-BotPNI-->
<ul>
<li>Prev by Date:
<strong><a href="msg00703.html">[ale] Penguinfest?</a></strong>
</li>
<li>Next by Date:
<strong><a href="msg00705.html">[ale] X running excruciatingly slow</a></strong>
</li>
<li>Previous by thread:
<strong><a href="msg00702.html">[ale] sshd resource intensive??</a></strong>
</li>
<li>Next by thread:
<strong><a href="msg00671.html">[ale] sshd resource intensive??</a></strong>
</li>
<li>Index(es):
<ul>
<li><a href="maillist.html#00704"><strong>Date</strong></a></li>
<li><a href="threads.html#00704"><strong>Thread</strong></a></li>
</ul>
</li>
</ul>

<!--X-BotPNI-End-->
<!--X-User-Footer-->
<!--X-User-Footer-End-->
</body>
</html>