[syslinux] gpxelinux.0 and slow HTTP performance on VMware ESX VM

[syslinux at schlomo.schapiro.org]

Hi,

Am 29.06.2011 22:05, schrieb H. Peter Anvin:
> On 06/29/2011 11:57 AM, Schlomo Schapiro wrote:
>>
>> The core problem is that HTTP transfers by gpxelinux.0 are very slow. Sadly this
>> problem seems to be somehow related to our VMware ESX environment and I am not
>> able to pin the problem down.
>>
> 
> The requirement for gpxelinux.0 to support HTTP transfers is going to be
> dropped in Syslinux 4.10, which is now on the release track.  Could you
> test out pxelinux.0 (*not* gpxelinux.0) from Syslinux 4.10-pre15 and see
> if you have any problems?
> 
> Other than that, it would be good to get a package trace
> (tcpdump/wireshark).

I tried your suggestion today (and I think it is a very good thing to
have native HTTP support in pxelinux).

Unfortunately it does not work. I put together some debug infos and
traces at http://files.schapiro.org/schlomo/syslinux/index.html

Things to notice:
* syslinux 4.10 did apparently not try to load vesamenu.c32 but
immediately tried vesamenu.c32.0 and other variations. The access log
shows that very nice. First you find there a successful boot with a user
agent of gPXE from gpelinux.0 4.04. After that the failed boot requests
from a user agent of Syslinux/4.10

* there are much less network errors in the pcap trace with pxelinux
4.10 compared to gpxelinux 4.04, but still some.

* I tried various VM settings with 32 and 64 bit and various NIC types,
seems to have no effect

* gpxelinux.0 4.04 HTTP performance differs very much between HW (fast)
and VM (slow). Could it be that the code is taxing the VM in a way that
makes the virtualization become very slow compared to hardware?

Kind Regards,
Schlomo