Re: [9fans] patch/create problem (error?)

["Antonin Vecera" <antonin.vecera@gmail.com>]

On Fri, Sep 12, 2008 at 1:47 PM, erik quanstrom <quanstro@quanstro.net> wrote:
>>>> I had problem to create a patch - the command didn't finish for long long time.
>>>
>>> I created a patch yesterday and it worked fine. It is fairly slow as it
>>> diff's all the files you have changed with those on sources.
>>>
>>> Sadly the 9p protocol is quite badly effected by high (intercontinential) RTTs.
>>>
>>> -Steve
>>
>> There were only 2 files in the patch. I wait for about 10 minutes and nothing.
>> But then I tried to copy a file from command line.
>> If I copied an ordinary file (to /n/sources) it was done immediately.
>> But If I copied a file from bind-ed(!) directory it was endless...
>> There was no diff, only copy file.
>
> i would guess the problem is a bit different.  i'm assuming that
> reads from sources work fine.  it's not until you try to write there
> that there's a problem.
>
> this sounds like a mtu problem.  i have a similar problem.
> i am not able to submit patches over one particular
> network interface.  however, if i use a lower mtu, things work fine.
> i believe this is because the dumpy dsl modem we have
> blocks icmp messages.
>
> you could lower the mtu on the interface, but rather than
> punishing all traffic, i wrote a program called cpmtu. cpmtu
> is attached.  if you define this function
>        fn cp {cpmtu -m 700 $*}
> before you run patch/create, i believe patch should work
> properly for you.
>
> as an aside: i don't think 9p itself limits plan 9 performance
> over high-latency links.  the limitations have more to do with
> the number of outstanding messages, which is 1 in the mnt
> driver.
>
> - erik
>

It seems you are right. I think I used in my previous tests too
specific (small) files.
I will try to play with mtu and with your "cpmtu".

Anyway, does 9P and Plan9 know about "path MTU discovery"?
Or have I something wrong at my firewall/router?
Other of my computers (FreeBSD,Windows) don't have such problems.

Antonin