[syslinux] Syslinux 4.04 gpxelinux.0 http performance problem with VMware VMs

[Andrew Bobulsky]

On Tue, May 8, 2012 at 8:24 AM, Pasi Kärkkäinen <pasik at iki.fi> wrote:
> On Tue, May 08, 2012 at 02:05:31PM +0300, Pasi Kärkkäinen wrote:
>> On Mon, May 07, 2012 at 09:53:35PM -0400, Gene Cumm wrote:
>> > On Mon, May 7, 2012 at 4:40 PM, Pasi Kärkkäinen <pasik at iki.fi> wrote:
>> > > Hello,
>> > >
>> > > In my testing environment I have two VMs on ESXi 5.0.
>> > >
>> > > VM A = dhcp/tftp/PXE/http server, running CentOS 6.2. Syslinux 4.04 with the included gpxelinux.0.
>> > > VM B = PXE boot client.
>> >
>> > > Any ideas what's causing the bad performance and those continuous retransmits?
>> > > Anything I should try to debug this?
>> > >
>> > > On baremetal with Intel NICs I've seen much better gpxelinux.0 download speeds over http.
>> >
>> > Syslinux 4.04 is obsolete and probably not worth debugging.  4.05 is
>> > current and 4.10-pre20 is a beta with lwIP, a lightweight IP stack,
>> > eliminating the need for gPXE if you only want HTTP downloads.  I've
>> > already been testing 4.10-pre* in VMware VMs with success after my
>> > patch.  I've seen a solid 45-70 MB/s after that patch on VMware VMs.
>> >
>>
>> That sounds really nice! I'll have to try the new stuff.
>>
>
> Oh, is there any documentation or examples about the new non-gPXE stuff?
> Should I just use pxelinux.0 to get the LwIP http?
>
> I couldn't find anything with "grep -i lwip doc/*" in the git clone,
> but maybe I'll start browsing the changelogs :)
>
>
> Thanks,
>
> -- Pasi


Hello Pasi,

As I understand it, simply chain pxelinux.0 (from the 4.10-pre* line)
to your PXE client as the boot file, and it'll speak HTTP if it's
given an HTTP URI from the pxelinux.cfg/default (or client specific
named) config file.

I'd suspect that if you want to pull HTTP for the config file as well,
you'd have to set your DHCP options accordingly, notably the pxelinux
Path Prefix, or DHCP option 210, along with the "pxelinux magic"
options.  Detailed here:
http://www.syslinux.org/wiki/index.php/PXELINUX#Can_I_send_information_to_PXELINUX_via_special_options_in_the_DHCP_response.3F

Been meaning to try it out myself since I downloaded the binaries a
few days ago :)

Best Regards,
Andrew Bobulsky