Re: Bizarre performance limitation

[Michael <macallan%netbsd.org@localhost>]

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Hello,

On Feb 26, 2010, at 4:34 PM, John Klos wrote:

> I've used NetBSD-macppc extensively and still have many machines  
> running it. However, the last time I had a PowerMac G4 tower running  
> NetBSD was quite a long time ago (pre-NetBSD 4, I believe). At one  
> point I had a tower saturating a 100 Mbps Internet connection while  
> serving video files via Apache, so I know they can be quite fast.
>
> Recently I set up a Quicksilver tower with 1.5 gigs of memory, a  
> 1.733 GHz 7448 accelerator, an ATTO UL3D 160 MB/sec UltraSCSI card,  
> a 64 bit Intel gigabit PCI card and NetBSD 5 so that I could do tape  
> backups over the network to an LTO-4 tape drive. However, it appears  
> I cannot get more than 7 or 8 MB/sec tops through the network.
>
> The machine providing NFS shares is an 8 core Xserve running Mac OS  
> X 10.6.2 with a direct gigabit connection. I've used the same  
> machine with an amd64 system running NetBSD to do tape backups  
> before, and I've been able to get at minimun 30 MB/sec.
>
> I've tried using 9000 byte frames (no difference), adjusting the  
> size of the NFS transfers, using / not using hardware checksumming,  
> and so on. The PowerPC system is 85% or more idle with 2% interrupt  
> and less than 15% system in top.
>
> The ethernet card is doing about 800-850 interrupts a second. With a  
> 9000 byte packet size and an 8k NFS transfer size, that makes for  
> about 6.5 to 7 MB/sec speed, which netstat bears out.
>
> Does anyone have any clue what might be so different between the  
> macppc system and an otherwise identical amd64 system which might  
> explain the disparity?

Hmm, I get consistently more than that out of my GigE G4 serving nfs  
over the onboard NIC, although throughput varies depending on the  
client - a G5 running OSX gets 12-15MB/s, a Blade 2500 running Solaris  
gets about 20-25MB/s. With the G4 running OSX the G5 gets 30-40MB/s  
though.
With an U60 running NetBSD as client I get significantly better  
performance using tcp mounts ( ~5.5MB/s vs. ~9.5MB/s through a hme, I  
don't have a well supported gigabit card to stick in there ).

just my 2c
Michael
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