Messages in this thread |  | | | Date | Mon, 14 Aug 2006 14:25:50 -0700 | | From | Ben Greear <> | | Subject | Re: Network compatibility and performance |
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linux-os (Dick Johnson) wrote:
> No it will return FAIL (-1) or an error and 0 (the bottom of the procedure) > if the whole things went. It is mandatory that the whole thing goes > so this procedure should handle any intermediate actions.
I see..I missed that part.
> Upon your advice, I may try to add select() although, on a write it > seems to be putting in user-space something that used to be handled > quite well in the kernel. I don't think the user should really care > about the kernel internals, whether or not the kernel happens to have > a buffer available.
Since you put it in non-blocking mode, you need the select() to throttle unless you want to busy spin. Whether you should have to actually put in in non-blocking mode or not is a different question.
>>I have no idea why you need to add the MIN() logic..and that seems like >>something that should not be required. >> > > It seems that some code 'thinks' that a large buffer of data is > an error and won't even try to send some anymore.
I have seen a problem where I can repeatedly hang a TCP connection when running at high speed. The tx queue is full or mostly full, and on the wire I only see 200kpps of duplicate acks. Can't reproduce it with anything other than my big complicated proprietary app, so it remains unfixed.
I am not sure if this is related to what you see or not..but could you check to see if there is lots of acks on the wire when this hang happens?
>>Even 112kbps sucks on a decent network. What is the speed of your >>network, what protocol are you using, if tcp, what is the latency >>of your network? >> > > > The network is a single wire about 8 feet long, connecting Intel gigibit > links on two identical computers (crossover cable). This link is TCP. > For high-speed data, I use UDP and I get a higher throughput because > there is no handshake. Thew latency is the latency of Linux. BTW, it's > only a gigaBIT link, you can divide that by 8 for gigabytes. I don't > know the actual bit-rate on the wires, if we assume 1GHz, the byte-rate > is only 125,000 bytes per second. Being able to use 89.6 percent of > that isn't bad at all.
You must be meaning to add a few more zeros to that number. If you are getting ~125,000,000 Bytes per second then you are doing OK.
Ben
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