Re: [Xen-users] how to disable batching of page table entries updates for guest OS

[Michael South <msouth@xxxxxxxxxx>]

What if count us zero?

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Michael South

msouth@xxxxxxxxxx

On May 8, 2011, at 22:27, Qiang Zeng <zengqiang.buaa@xxxxxxxxx> wrote:

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!

Qiang.

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