proxmox kernel under vmware

ahoyer2

Active Member
Sep 6, 2006
14
0
41
USA
We're running several linux virtual machines under linux and have found that VMware server does not scale well with multiple guests on the same server. Even when the guests are idle, once a certain number of running guests is reached, the host CPU usage will climb exponentially. It is believed that one source of high CPU usage is that linux version 2.6 kernels are by default compiled with a system interrupt frequency of 1000 HZ. That's 1000 interrupts per second. Version 2.4 kernels had an interrupt frequency of 100 HZ, so there should be no serious side effects from restoring the slower interrupt frequency.

We have recompiled kernels with great success under CentOS, but haven't been able to get this fixed on the proxmox virtual machine.

Woud it be possible to recompile the proxmox kernel for virtual machines to lower the interrupt frequency?

Here's the patch we apply to our CentOS machines (different kernel version but it should pretty much be the same on 2.6.15)

Any help would be greatly appreciated.

Alex.

--- linux-2.6.9/include/asm-i386/param.h
+++ linux-2.6.9/include/asm-i386/param.h
@@ -2,7 +2,7 @@
#define _ASMi386_PARAM_H

#ifdef __KERNEL__
-# define HZ 1000 /* Internal kernel timer frequency */
+# define HZ 100 /* Internal kernel timer frequency */
# define USER_HZ 100 /* .. some user interfaces are in "ticks" */
# define CLOCKS_PER_SEC (USER_HZ) /* like times() */
#endif
 
You are right, but newer 2.6 kernels (>2.6.11 AFAIK) are by default 100Hz. Proxmox uses kernel 2.6.15, thus frequency is 100Hz.


- Dietmar
 

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