Autoconf painfully slow on Ubuntu 10.04

[Cyberaw]

Hi everyone !
I'm new to Virtualbox: I've enjoyed using it for a few days but I've discovered that compiling in a Linux guest is terribly slow.

Autoconf (./configure) is painfully slow (1 or 2 lines per second) and I would like to know what happens.
It seems that compiling the C files is actually faster than doing a single configure step.
I am compiling software like binutils, ncurses, DirectFB and the linux kernel.

System time seems to be where the majority of the CPU time is spent, and top is showing that bash is the guilty one (usually in multiples instances, >4).
Is there a way to pinpoint the actual bottleneck ? I assume top is not the best tool for that ...

Thanks in advance !

Host Info:
Windows XP sp3 32bits
Intel Core2 Quad Q6850 3.0Ghz
4GB ram
Vbox 3.2.10 r66523 PEUL

Guest:
Ubuntu 10.04 32bits + Guest Additions
1GB Ram, Dynamic VMDK, 4 CPUs, VT-x and Nested paging ON

[Perryg]

VMDK is slower in VirtualBox than VDI and you probably need to assign a bit more memory. Try (2GB)
Compiling on a VM is slower than metal but from what you are saying it is not that slow. I usually get around 60% to 70% depending on what I am compiling.
4 processors on the guest could actually slow you down a bit too. Try with 2 or even 1 depending on how many real processors you have (not cores).

[Cyberaw]

Thanks for the quick reply, I'll try to lower the core count.
Would it be worth it to convert the VMDK file to VDI ?

[Perryg]

Try it both ways. I did and found the VDI a lot more responsive in VirtualBox. Of course YMMV.

[Cyberaw]

Wow, you were right, down to two CPUs the ./configure and compile time is significantly faster... here's some numbers :
Some numbers are a bit strange, but eh, I'm comparing oranges to oranges right now... feel free to suggest another benchmark test !

Code: Select all

4 CPUs :
# time ../directfb-1.2.8/configure > log
real    1m28.886s
user    1m7.716s
sys     1m20.401s

# time make -j4 > log
real    5m46.558s
user    10m11.402s
sys     10m8.362s

# time make -j2 > log
real    3m31.060s
user    4m41.218s
sys     5m0.215s


2 CPUs :
# time ../directfb-1.2.8/configure > log
real    1m10.440s
user    0m33.862s
sys     0m52.211s

# time make -j2 > log
real	2m2.630s
user	1m34.390s
sys     2m11.592s

# time make > log
real    2m31.647s
user    1m27.921s
sys     1m58.763s


1 CPU :
# time ../directfb-1.2.8/configure > log
real    1m14.855s
user    0m30.998s
sys     0m41.547s

# time make > log
real    2m47.232s
user    1m21.901s
sys     1m33.438s

It seems that 2 cpus and -j2 is the best option.
I didn't test with more than 1GB of ram since 'free' reports always >500mb of free memory.

Edit: converting the VMDK to a VDI gave me the same benchmark results for configure and compilation (using 2 cores/jobs).