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

Jonathan Helman
Thu, 12 Apr 2018 00:24:27 -0000

On 04/10/2018 08:12 PM, Jason Wang wrote:
>
>
> On 2018?04?10? 05:11, Jonathan Helman wrote:
>>
>>
>> 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
>
> Hi Jon:
>
> Have you tested new driver with old qemu?

Yes, this testing scenario looks good. Thanks.

Jon

>
> Thanks
>
>