Syslinux - Feb 2014 - Very slow download with pxelinux > 4.07 on specific hardware

Notice the same thing happens with optiplex 790 (core i5 sandy bridge).

With 790 too everything is ok with pxelinx 4.0.7.

I'll post a wireshark later.

Le 25/02/2014 17:06, H. Peter Anvin a ?crit :
> On 02/25/2014 07:45 AM, H. Peter Anvin wrote:
>> On 02/25/2014 07:07 AM, Eric PEYREMORTE wrote:
>>> I did some additional tests :
>>>
>>> On a dell optiplex 380, i disabled internal nic, added a 3com 905c
tx
>>> external pci nic : very slow too.
>>> On a dell 740(which is always fast), i put the 3com to be sure :
very fast.
>>>
>>> So it seems it is not related to the nic itself. To be sure it
wasn't
>>> just one failing computer i tested several 380.
>>>
>>> I tried disabling several features in bios, like Execute Disable,
>>> multicore support, speedstep... Nothing helped.
>>>
>>> I thought at the beginning it was an efi problem (althought i use
it in
>>> bios mode), but on optiplex 7010 which is efi based too, i
don't have
>>> the problem...
>>>
>>> I used 6.03pre2 for this test.
>>>
>>> As i said previously no problem before version 5.00.
>>>
>> OK, this is extremely surprising.  Normally the NIC card BIOS is what
>> matters for PXE performance, but it sounds like in your case there is
>> something going on in the main BIOS that is causing problems.
>>
> What I'm at a loss for is *how* that would happen.  The biggest
> difference that I can think of is in the layout of the memory, but that
> shouldn't cause that kind of thing.
>
> Sending the wireshark trace might be useful, it certainly can't hurt.
>
> If there is a lost interrupt somehow that might explain the problem, but
> that shouldn't be related to Syslinux 4 vs 5/6 in any way...
>
> 	-hpa
>
>
>

-- 
Eric PEYREMORTE
Technicien Informatique - CRI
http://www.iut-valence.fr
T: 04.75.41.88.37

On 02/25/2014 08:31 AM, Eric PEYREMORTE wrote:
> Notice the same thing happens with optiplex 790 (core i5 sandy bridge).
> 
> With 790 too everything is ok with pxelinx 4.0.7.
> 
> I'll post a wireshark later.
The common thread seems to be Dell...

	-hpa

Hi,

We only have Dell computers here. We have about 100 optiplex 380.

Here is a link to download my wireshark traces :
http://dl.free.fr/qgCPEM5Uo

In this traces i tested pxelinux and lpxelinux 6.03 on optiplex 740(the 
one working)
and optiplex 380.

pxelinux works on both computers but very slowly on 380 as seen in traces.

lpxelinux works only on 740. On 380 it seems to enter in a kind of loop 
: the client computer sending Acknowledgement for a block continuously 
(but not for every block)

for lpxelinux on 380, it took 2 traces. One on the server, and one on a 
hub i connected to the client. (note the problem happen even without the 
hub and on all 380 computers)

Cheers

Le 26/02/2014 01:15, H. Peter Anvin a ?crit :
> On 02/25/2014 08:31 AM, Eric PEYREMORTE wrote:
>> Notice the same thing happens with optiplex 790 (core i5 sandy bridge).
>>
>> With 790 too everything is ok with pxelinx 4.0.7.
>>
>> I'll post a wireshark later.
> The common thread seems to be Dell...
>
> 	-hpa
>
>
>