On 02/01/2012 01:12 PM, Takuya Yoshikawa wrote: > (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. True. But let's not add more locks. > > Isn't it possible to make others hold the lock only for the case of > marking to the bitmap? (I will check myself too.) Yes, in walk_addr(), while setting accessed and dirty bits in guest PTEs, or while emulating instructions and writing to guest memory. >> That'll be great, numbers are better than speculation. >> > > > Yes, I already have some good numbers to show (and some patches). Looking forward. -- error compiling committee.c: too many arguments to function -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
