Why is the newer bootmgr.exe so slow?

[joakim]

I just noticed that newish bootmgr.exe now is significantly slower than previous versions when pxe booting. What I have come to conclude is that vista sp0 and longhorn performs much better than say server 2008 (sp1) and windows 7 rc1. Taking account for other things too, I would say the longhorn version (6.0.5259.0 in this case) is by far the best out of the 4 versions tested.

Is this something others can verify as well?

One thing is that other solutions boot winpe3 much faster than bootmgr.exe/wim over the same protocol (pxe/tftp). Another thing is that the newer bootmgr.exe performs much worse than previous versions.

More details can be found at the later replies of this thread; http://sanbarrow.com/phpBB2/viewtopic.php?t=1705

Btw, the pxeboot.x can be from any version as they all boot all versions of bootmgr.exe.

I may have missed something obvious and important, but I must say the results are rather strange..

Joakim

[Tripredacus]

It looks like that site is all about booting via Nix hosts. I am not sure what you mean by bootmgr being slower in 7 but honestly I never used RC version of PE. If there is a significant increase to bootmgr time, it seems to be offset by total client boot time. For example, our WinPE 2.1 images take about 5-6 minutes to boot, but the WinPE 3.0 images are more like 3 minutes. Also, I am wondering if there is a speed difference between using Server 2008 vs a PXE Linux solution.

[joakim]

Actually all that is on a windows xp host giving dhcp with tftpd32. The chainloader (pxelinux.0) is just there to produce a multi menu (menu.c32) as base for whatever to be tested and optionally further chained. Just like pxelinux.0 -> pxeboot.0 instead of serving pxeboot.X (or similar) directly over dhcp as the bootfile. Which makes it easier when you want to have other chainloaded solutions in the same menu.

If you are using wds (which I'm not that familiar with), you will likely have some of the bootfiles (x.n12 or x.com) served on dhcp, which in turn loads bootmgr.exe for the actual network transfer and mounting of the wim. Since these bootfiles are not version-tied they can boot whatever version of bootmgr.exe, at least on my machine.

Don't you notice any difference in performance when changing the version of bootmgr.exe? Particularly with the older versions mentioned.. As far as I know, bootmgr.exe don't care about what OS is inside the wim, as long as it is an nt6.x.

Btw, how big are those winpe2.1/winpe3.0 images?

Joakim

Edited March 29, 2010 by joakim

[cluberti]

No, using WDS and WinPE 3.0 is far faster than it was with WinPE 2.0, and transfer speeds seem better to once within the PE. I'm guessing the speed difference may exist in your implementation of deployment, specifically a client OS with a non-native PXE client.

[joakim]

So you suggest the difference may come from the fact that the combination xp/tftpd32/dhcp/pxe is not at natively supported feature on the server side?

I understand that it would decrease the performance in an absolute and overall level. However in these tests all other variables are held constant, only changing the version of bootmgr.exe. The results are from repeated tests changing back and forth the version changes. And performance on each version are always the same, with rather large predictable differences on those mentioned versions. The combination of a chained grub.exe/iso was always the fastest, and beating all versions of a standard booted winpe.

Maybe I'll create a dummy wds environment and look into this, if I get the time..

Joakim

[cluberti]

You have to remember that the bootmgr code is expecting to boot from either local media or WDS - it's not designed with anything else in mind, so you may be hitting all kinds of problems when you change up the underlying infrastructure, no matter how closely it portends to emulate the native environment (in this case, WDS) that WinPE would boot from.

[Tripredacus]

I wanted to follow up that I do not get to experiment like a lot of you guys can. I need to make sure everything is current in order to obtain support for any problems I encounter. I could do things like this (like changing the boot rom) on my dev server but I wouldn't ever get the time to do it!