[Nottingham] Random Windows-y network-y/file IO-y question

Martin martin at ml1.co.uk
Thu Oct 31 17:28:24 UTC 2013

On 31/10/13 17:21, Martin wrote:
> On 31/10/13 15:08, Jason Irwin wrote:
>> Is there some kind of Windows network bandwidth limit per thread of
>> execution? i.e. per connection from the same client.
>> And I mean over and above what the firewalls etc might be imposing.
>> Or is there some per limit on file IO per thread?
>> Something tells me there is, but for the friggin' life of me I can find
>> the sodding documentation.
>> I did stumble across SMB multichannel docs which look interesting.  Will
>> have to see if Samba support that in a bit.
> On the networking side, there is a physical limit imposed by the link
> latency for getting ack packets back and the max number of data packets
> allowed in flight... Windows has had problems with that in the past as
> networks speed has increased whilst we are still stuck on the imposed
> 'industry standard' 1500 max packet size. There's been a few
> work-arounds but you are still stuffed if you are suffering high latency.

You mention firewalls which suggests you're going beyond your LAN but
also note:

The 1500byte max packet size imposition means that you need either an
awful lot of packets in flight or silly-fast hardware to be able to
saturate Gbit speed LANs. Hence one trick is to use "Jumbo packets".

Unfortunately, certain systems and some hardware still are still a long
way behind such advancements...

Good luck,

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