Re: [PATCH] bug fix for efi network

[Bean]

2012/4/30 Vladimir 'φ-coder/phcoder' Serbinenko <address@hidden>:
> On 29.04.2012 10:22, Bean wrote:
>> Hi,
>>
>> This patch fix a few bugs in efinet.
>>
>> It also change the tftp block size from 1024 to 8192, which would
>> result in HUGE speed difference. In my previous testing, the larger
>> the block size, the faster the speed. It can reach up to 60-70MB/s in
>> 1Gb ethernet when block size is about 60K, therefore it would be a
>> good idea to allow user to configure this parameter. The native tftp
>> service in UEFI use a default block size of 8192.
> 8192 is bigger than the MTU on most cards so it results in fragmentation
> or it emits jumbo packets. It's unclear how both network and server
> would react to this.
> Moreover the optimal packet size is in any case:
> k * (mtu - ip_header_size - udp_header_size - tftp_header_size)
> where k is some number. Only these number result in fully sized packets.
> k=1 result in best available option for non-fragmented packets. k > 1
> can create some preload by abusing fragmentation.
> Note that some servers do preload by other means and k > 1 with such
> servers would result in slowdown.

Hi,

I believe server would split the packets into multiple fragment, each
within mtu to pass through network, and client assemble them to get
the original packet. Large block would reduce the number of
handshakes, and since nic has buffer to cache multiple packets, it
allows network driver and nic card to work in parallel and thus hide
some of the network traffic.

Perhaps users with real UEFI implementation can try out different
block size setting and reports the result.

-- 
Best wishes
Bean