BETA2 - Abysmal speed on Centos5 guest

[Technologov]

No, you don't need to create new VM... same SATA VM can run on IDE controller.
But not vice-versa - if you installed with IDE, you have to reinstall.

Just remove SATA controller, and attach the VDI to IDE controller.

[_litz]

Ok ...

I've done so (disabled our company software so it wouldn't try and run on an IDE drive) and observed no difference in speed.

Takes the same slow amount of time as on SAS, SCSI or SATA.

If I have time, tomorrow or maybe this weekend I will try a fresh new Centos image and repeat.

- _litz

[Technologov]

I think it won't improve things... we need to understand what causes problems...

maybe some conflicting driver...
can you send me the output of "lsmod | sort" ?

Anyway, as you see from my numbers, I was able to achieve 67% of real hardware performance.
I don't understand why your numbers should be different.

[Technologov]

OK, dude, where do we proceed from here?

For now it seems, that VirtualBox is only slow on your setup.
esp. striking difference is install of Linux Additions -
it takes you 45 min, while only 70 seconds here...

[Hrvoje]

Hi.

Sorry to reopen an old thread, but i did hit the same problem - hardware on which VMWare works flawleslly, and VBox is just pain to use and see.

HW is HP DL580 G5 (Intel(R) Xeon(R) CPU X7350 @ 2.93GHz).

I suspect that problem is with how vCPU is presented to OS. VMWare presents vCPU as physically separate CPU's (KVM does the same), while VBox presents them as all on one physical package - that is, if you assign 4 vCPU, VBox present them as 4 cores of signle CPU.

Now, this seems as fairly small thing, but it could actually have HUGE implication on guest OS, because of optimizations used by guest. I did open a ticket for this - 13024. Please, read it!

Also, i did found out that putting:

Code: Select all

clearcpuid=0x1c

in guest boot parameters does help, and guest have somewhat better performance. This one line disables HT in guest - and this is what also VMWare (and KVM) does by default.

Also, it seems that host have huge interrupt storming - caused by LOC interrupts. In idle, this is less than 100, but with 4 VM's, it is constant around 60k! Yes, 60k interrupts!!

_litz, could you try this, if you still have this vm's?

I did try also the same guest on i7 capable HW, and it does fly ... really.

Regards,

H.