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Date:      Fri, 2 Oct 2009 19:24:38 +0700
From:      Yohanes Nugroho <>
To:        Stanislav Sedov <>
Subject:   Re: FreeBSD ARM network speed
Message-ID:  <>
In-Reply-To: <>
References:  <>  <>

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On Fri, Oct 2, 2009 at 4:35 PM, Stanislav Sedov <> wrote:
> On Fri, 2 Oct 2009 12:58:38 +0700
> Yohanes Nugroho <> mentioned:
>> I have two question:
>> 1. Is the network speed in Freebsd ARM currently slower than Linux ARM?
> I don't think so. =C2=A0Our network stack is arch-independent and should =
> equally well on all platforms. =C2=A0I've been able to acchieve speeds up=
> 70 Mbps on my 180Mhz AT91 based board which uses very plain and dumb
> ethernet controller (although, DMA is supported).

Ok, glad to hear that :) because the first time I asked about a
problem in the USB, it turns out that there was a problem in the
latest source code in busdma, and I have spent several days thinking
it was my bug.

> This looks weird. =C2=A0Why do you stop the TX engine to add more packets
> in the ring? =C2=A0This thing definitely can kill the network performace

yes, you are right, that is weird, I will have a look at it again.

> The main strategy of the driver should be to keep the ring filled,
> waking up when some reasonable amount of space in the ring become
> available, and sleeping all other time when the adapter is working.

Thank you for your enlightenment.

> I'm not sure why Linux doesn't use interrupt, but this looks really
> wrong.

It is because the driver comes from a vendor (very messy code), not in
the mainline kernel yet.

the background story:
- I have a cheap chinese NAS device (Agestar NCB3AST, cost about $50,
now you can get it for about $40), comes with linux kernel 2.4, no
source code was given. SoC used is Starsemi 9104
- I found out that there is a Linux source code for this SoC but for
different device (with different hardware around the SoC).
- Based on the source code, I ported it to work on Linux kernel 2.6, I
didn't bother to try to clean up the source code
- I am thinking of trying to add my code to mainline kernel, I
realized that I didn't understand most of the source code
- Bruce Simpson offered a device with same SoC (NSD-100) and I tried
to port FreeBSD to it, thinking that I will understand the SoC better
when rewriting the code
- Starsemi was bought by cavium, the SoC is renamed to Econa CNS1102,
and the datasheet was released. The datasheet is not very clear, so I
am still basing some of my code on the Linux code (just the logic, not
copy pasting, I understand about the license implication).

> I'd suggest you to ananlyze the performance of network driver
> either by using the profiling tools available (kgmon, hardware
> counters (if any)) or/and via system monitoring tools (top, etc).
> Top, in particular, will allow you to see where all the CPU time
> went.

I am testing in single user mode. Last time i tested using kgmon, it
doesn't show any particular area that might cause the slowdown.

Once again, thank you, I now have some ideas on what to do this weekend.


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