Date: Thu, 19 Oct 1995 17:05:19 -0500 From: Jon Loeliger <jdl@chrome.onramp.net> To: davidg@Root.COM Cc: questions@freebsd.org Subject: Slow throughput Message-ID: <199510192205.RAA15051@chrome.jdl.com> In-Reply-To: Your message of "Thu, 19 Oct 1995 13:07:20 PDT." <199510192007.NAA29801@corbin.Root.COM>
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[Moved to questions from hackers]
Apparently, David Greenman scribbled:
> Let me add a bit of sanity to this part of the discussion. 115200 baud async
> will give you about 11.52Kbytes/second if you have no packet overhead. 115200
> baud sync will give you 14.40Kbytes/second if you have no packet overhead.
> Why? Because we're talking bits - async is 8 data bits plus 1 start and 1
> stop bit...10 bits. With synchronous serial, it's just 8 data bits. So sync
> always has the potential to give you 25% more bytes throughput at the same
> bit rate compared to async.
> Now with sync you'll also be running at a faster bit rate (128000bits/sec).
> This is 16Kbytes/second. This is 38.9% faster.
OK, it's pretty clear now that I might have a mysteriously slow component
to my system's network (?) throughput. How do I find it? I've got ISDN,
usually at 64kb/sec but BOND-able to 128kb/sec connected to a pipeline-50
which is spewing ethernet to a 10BaseT hub. My machine is on the hub
with one other machine now. I've got a Linksys Ether 16 NE2000 card
hanging off the ISA bus.
At 64k ftp suggests a sustained rate of about:
41539 bytes received in 23 seconds (1.8 Kbytes/s)
1936621 bytes received in 8.9e+02 seconds (2.1 Kbytes/s)
It is somewhat slow, isn't it?
What's the slow part of this equation? ISDN, P-50, ether, ISA, or
writing to my IDE disks (WD 31000)?
I suspect that the ether card on the ISA bus is the slow part here.
However, when I get a 128k line, I *do* get about 4k/sec throughput.
Does this fact alone point at, like, the IDE disk.
How can I find out? Ie, which performance monitoring tool or
benchmark should I run to really place the blame? :-) What piece
of this picture should I replace first?
If I wanted to improve things, and was thinking about a PCI SCSI
card anyways (tape backup), what might I do? (I also have a 3Com
Etherlink III lovely 3c509B on hand too.)
Thanks,
jdl
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