Re: [Qemu-devel] [qemu-s390x] [PATCH v2 0/4] pc-bios/s390-ccw: Allow network booting via pxelinux.cfg

[Thomas Huth <thuth@redhat.com>]

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On 13.06.2018 12:56, Viktor VM Mihajlovski wrote:
> On 12.06.2018 08:17, Thomas Huth wrote:
>> On 11.06.2018 14:03, Viktor VM Mihajlovski wrote:
> [...]
>>
>> If you have the time to look at the traffic, could you please also check
>> the TFTP block size option that is negotiated at the beginning of the
>> TFTP transfer? If this other client is negotiating a transfer block size
>> that is bigger than the one from the s390-ccw firmware, this could
>> explain the differences in the downloading time, too.
>>
>> libnet from SLOF currently uses a block size of 1428. This is the size
>> where all TFTP data should still fit nicely into one ethernet packet -
>> and this is also the size which is still supported by all TFTP servers
>> that support the blksize option. But theoretically it's also possible to
>> use a bigger block sizes if both, the server and the client support
>> fragmented UDP packets. Unfortunately, as far as I can see, SLOF's
>> libnet does not support fragmented UDP packets, so we can't increase the
>> block size here anymore so easily.
>
> You will be pleased to hear that the SLOF TFTP client outperforms the
> busybox version (which uses 544-byte packets) by 30%. There's some
> randomness introduced by the differences in DHCP response times which is
> clearly not the client's fault. All is good...

Ah, great, thanks for checking!

So I'm going to prepare a pull request for this next...

 Thomas


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