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

From: Jason Wang
Date: Tue Apr 10 2018 - 23:12:14 EST



On 2018å04æ10æ 05:11, Jonathan Helman wrote:


On 03/22/2018 07:38 PM, Jason Wang wrote:


On 2018å03æ22æ 11:10, Michael S. Tsirkin wrote:
On Thu, Mar 22, 2018 at 09:52:18AM +0800, Jason Wang wrote:
On 2018å03æ20æ 12:26, Jonathan Helman wrote:
On Mar 19, 2018, at 7:31 PM, Jason Wang<jasowang@xxxxxxxxxx>Â wrote:



On 2018å03æ20æ 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@xxxxxxxxxx>
Reviewed-by: Jason Wang<jasowang@xxxxxxxxxx>
Thanks.

---
ÂÂ drivers/virtio/virtio_balloon.cÂÂÂÂ | 6 ++++++
ÂÂ include/uapi/linux/virtio_balloon.h | 4 +++-
ÂÂ 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)
ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ pages_to_bytes(events[PSWPOUT]));
ÂÂÂÂÂÂ update_stat(vb, idx++, VIRTIO_BALLOON_S_MAJFLT, events[PGMAJFAULT]);
ÂÂÂÂÂÂ update_stat(vb, idx++, VIRTIO_BALLOON_S_MINFLT, events[PGFAULT]);
+#ifdef CONFIG_HUGETLB_PAGE
+ÂÂÂ update_stat(vb, idx++, VIRTIO_BALLOON_S_HTLB_PGALLOC,
+ÂÂÂÂÂÂÂÂÂÂÂ events[HTLB_BUDDY_PGALLOC]);
+ÂÂÂ update_stat(vb, idx++, VIRTIO_BALLOON_S_HTLB_PGFAIL,
+ÂÂÂÂÂÂÂÂÂÂÂ events[HTLB_BUDDY_PGALLOC_FAIL]);
+#endif
ÂÂ #endif
ÂÂÂÂÂÂ update_stat(vb, idx++, VIRTIO_BALLOON_S_MEMFREE,
ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ 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 {
ÂÂ #define VIRTIO_BALLOON_S_MEMTOTÂÂ 5ÂÂ /* Total amount of memory */
ÂÂ #define VIRTIO_BALLOON_S_AVAILÂÂÂ 6ÂÂ /* Available memory as in /proc */
ÂÂ #define VIRTIO_BALLOON_S_CACHESÂÂ 7ÂÂ /* Disk caches */
-#define VIRTIO_BALLOON_S_NRÂÂÂÂÂÂ 8
+#define VIRTIO_BALLOON_S_HTLB_PGALLOCÂ 8Â /* Hugetlb page allocations */
+#define VIRTIO_BALLOON_S_HTLB_PGFAILÂÂ 9Â /* Hugetlb page allocation failures */
+#define VIRTIO_BALLOON_S_NRÂÂÂÂÂÂ 10
ÂÂÂÂ /*
ÂÂÂ * 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?

Thanks