Xen has a perf. enhancement by batching page table updates for the guest OS. I'm trying to measure the impact on the guest OS's performance, when this enhancement is disabled.
But I don't know how to disable it. I tried modifying do_mmu_update in xen/arch/x86/mm.c, which is to process the batch of page table updates requested by the guest OS. I simply limit it to only process one update:
<< for ( i = 0; i < count; i++ )
>> for ( i= 0; i < 1; i++)
However, after I install this version, there is a kernel panic.
An alternative may be to modify the code in the paravirtualized guest OS code, but I prefer to change xen code. Or do I HAVE to change the OS code rather than xen?
Could somebody provide some hints? Thanks!