(2012/02/01 20:01), Avi Kivity wrote:
On 02/01/2012 01:00 PM, Takuya Yoshikawa wrote:
How about just doing:
take a spin_lock
copy the entire (or some portions of) bitmap locally
clear the bitmap
unlock
That means that vcpus dirtying memory also have to take that lock, and
spin while the bitmap is being copied. So kvm_vm_ioctl_get_dirty_log()
will become faster, at the expense of vcpus, which I think is a bad
tradeoff.
Almost every caller is already holding the mmu_lock.
Isn't it possible to make others hold the lock only for the case of
marking to the bitmap? (I will check myself too.)
write protect the dirty pages based on the copied dirty data
copy_to_user
I can show you some performance numbers, this weekend, if you like.
That'll be great, numbers are better than speculation.
Yes, I already have some good numbers to show (and some patches).
Takuya
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