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

[Andrew Stuart]

On 6/30/2011 7:53 AM, syslinux at schlomo.schapiro.org wrote:
> 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


Did you try the above without gPXE/gpxelinux.0 ? Your logs indicate you 
are still using gPXE. It's my understanding that a wrapper is not needed 
for 4.10 since it has native http (I haven't had the chance to 
personally try it).

If for some reason you do need gPXE, I might suggest you try 
www.ipxe.org as gPXE is 'dead', ipxe was forked, and is actively being 
contributed to and maintained. Many issues with gPXE have been corrected
in iPXE.

Lastly, Trolling these lists [syslinux|ipxe] I have seen mention that 
vmware's pxe stack leaves a lot to be desired. I know from personal
experience with Workstation [6|7], and esxi [3|4] that pxe booting is 
slightly slower then real hardware, but it's been 'fast enough' that I 
haven't tried to look into it further.

As a curious side thought, I wonder if anyone has tried to replace 
vmwares pxe option rom with gPXE/iPXE...

-A