Re: [PATCH V4 4/5] kvm/stats: Add provisioning for ulong vm stats and u64 vcpu stats

[Christian Borntraeger <borntraeger@de.ibm.com>]

On 07/19/2016 10:12 AM, Suraj Jitindar Singh wrote:
> vms and vcpus have statistics associated with them which can be viewed
> within the debugfs. Currently it is assumed within the vcpu_stat_get() and
> vm_stat_get() functions that all of these statistics are represented as
> u32s, however the next patch adds some u64 vcpu statistics.
> 
> Change all vcpu statistics to u64 and modify vcpu_stat_get() accordingly.
> Since vcpu statistics are per vcpu, they will only be updated by a single
> vcpu at a time so this shouldn't present a problem on 32-bit machines
> which can't atomically increment 64-bit numbers. However vm statistics
> could potentially be updated by multiple vcpus from that vm at a time.
> To avoid the overhead of atomics make all vm statistics ulong such that
> they are 64-bit on 64-bit systems where they can be atomically incremented
> and are 32-bit on 32-bit systems which may not be able to atomically
> increment 64-bit numbers. Modify vm_stat_get() to expect ulongs.
> 
> Signed-off-by: Suraj Jitindar Singh <sjitindarsingh@gmail.com>

Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>