[virtio-dev] Re: [PATCH v2] virtio_balloon: export hugetlb page allocation counts

Jonathan Helman
Mon, 09 Apr 2018 21:11:19 -0000

On 03/22/2018 07:38 PM, Jason Wang wrote:
>
>
> On 2018?03?22? 11:10, Michael S. Tsirkin wrote:
>> On Thu, Mar 22, 2018 at 09:52:18AM +0800, Jason Wang wrote:
>>> On 2018?03?20? 12:26, Jonathan Helman wrote:
>>>>> On Mar 19, 2018, at 7:31 PM, Jason Wang<jasowang at
redhat.com>? wrote:
>>>>>
>>>>>
>>>>>
>>>>> On 2018?03?20? 06:14, Jonathan Helman wrote:
>>>>>> Export the number of successful and failed hugetlb page
>>>>>> allocations via the virtio balloon driver. These 2
counts
>>>>>> come directly from the vm_events HTLB_BUDDY_PGALLOC and
>>>>>> HTLB_BUDDY_PGALLOC_FAIL.
>>>>>>
>>>>>> Signed-off-by: Jonathan Helman<jonathan.helman at
oracle.com>
>>>>> Reviewed-by: Jason Wang<jasowang at redhat.com>
>>>> Thanks.
>>>>
>>>>>> ---
>>>>>> ?? drivers/virtio/virtio_balloon.c???? | 6 ++++++
>>>>>> ?? include/uapi/linux/virtio_balloon.h | 4 +++-
>>>>>> ?? 2 files changed, 9 insertions(+), 1 deletion(-)
>>>>>>
>>>>>> diff --git a/drivers/virtio/virtio_balloon.c
>>>>>> b/drivers/virtio/virtio_balloon.c
>>>>>> index dfe5684..6b237e3 100644
>>>>>> --- a/drivers/virtio/virtio_balloon.c
>>>>>> +++ b/drivers/virtio/virtio_balloon.c
>>>>>> @@ -272,6 +272,12 @@ static unsigned int
>>>>>> update_balloon_stats(struct virtio_balloon *vb)
>>>>>> ?????????????????? pages_to_bytes(events[PSWPOUT]));
>>>>>> ?????? update_stat(vb, idx++, VIRTIO_BALLOON_S_MAJFLT,
>>>>>> events[PGMAJFAULT]);
>>>>>> ?????? update_stat(vb, idx++, VIRTIO_BALLOON_S_MINFLT,
>>>>>> events[PGFAULT]);
>>>>>> +#ifdef CONFIG_HUGETLB_PAGE
>>>>>> +??? update_stat(vb, idx++,
VIRTIO_BALLOON_S_HTLB_PGALLOC,
>>>>>> +??????????? events[HTLB_BUDDY_PGALLOC]);
>>>>>> +??? update_stat(vb, idx++,
VIRTIO_BALLOON_S_HTLB_PGFAIL,
>>>>>> +??????????? events[HTLB_BUDDY_PGALLOC_FAIL]);
>>>>>> +#endif
>>>>>> ?? #endif
>>>>>> ?????? update_stat(vb, idx++, VIRTIO_BALLOON_S_MEMFREE,
>>>>>> ?????????????????? pages_to_bytes(i.freeram));
>>>>>> diff --git a/include/uapi/linux/virtio_balloon.h
>>>>>> b/include/uapi/linux/virtio_balloon.h
>>>>>> index 4e8b830..40297a3 100644
>>>>>> --- a/include/uapi/linux/virtio_balloon.h
>>>>>> +++ b/include/uapi/linux/virtio_balloon.h
>>>>>> @@ -53,7 +53,9 @@ struct virtio_balloon_config {
>>>>>> ?? #define VIRTIO_BALLOON_S_MEMTOT?? 5?? /* Total
amount of memory */
>>>>>> ?? #define VIRTIO_BALLOON_S_AVAIL??? 6?? /* Available
memory as in
>>>>>> /proc */
>>>>>> ?? #define VIRTIO_BALLOON_S_CACHES?? 7?? /* Disk caches
*/
>>>>>> -#define VIRTIO_BALLOON_S_NR?????? 8
>>>>>> +#define VIRTIO_BALLOON_S_HTLB_PGALLOC? 8? /* Hugetlb
page
>>>>>> allocations */
>>>>>> +#define VIRTIO_BALLOON_S_HTLB_PGFAIL?? 9? /* Hugetlb
page
>>>>>> allocation failures */
>>>>>> +#define VIRTIO_BALLOON_S_NR?????? 10
>>>>>> ???? /*
>>>>>> ??? * Memory statistics structure.
>>>>> Not for this patch, but it looks to me that exporting such
nr
>>>>> through uapi is fragile.
>>>> Sorry, can you explain what you mean here?
>>>>
>>>> Jon
>>> Spec said "Within an output buffer submitted to the statsq,
the
>>> device MUST
>>> ignore entries with tag values that it does not recognize". So
exporting
>>> VIRTIO_BALLOON_S_NR seems useless and device implementation can not
>>> depend
>>> on such number in uapi.
>>>
>>> Thanks
>> Suggestions? I don't like to break build for people ...
>>
>
> Didn't have a good idea. But maybe we should keep VIRTIO_BALLOON_S_NR
> unchanged, and add a comment here.
>
> Thanks

I think Jason's comment is for a future patch. Didn't see this patch get
applied, so wondering if it could be.

Thanks,
Jon