On 22.04.24 09:42, zhenwei pi wrote:
All the VM events related statistics have dependence on
'CONFIG_VM_EVENT_COUNTERS', once any stack variable is required by any
VM events in future, we would have codes like:
  #ifdef CONFIG_VM_EVENT_COUNTERS
       unsigned long foo;
  #endif
       ...
  #ifdef CONFIG_VM_EVENT_COUNTERS
       foo = events[XXX] + events[YYY];
       update_stat(vb, idx++, VIRTIO_BALLOON_S_XXX, foo);
  #endif

Separate vm events into a single function, also remove
'CONFIG_VM_EVENT_COUNTERS' from 'update_balloon_stats'.

Signed-off-by: zhenwei pi <pizhen...@bytedance.com>
---
  drivers/virtio/virtio_balloon.c | 44 ++++++++++++++++++++++-----------
  1 file changed, 29 insertions(+), 15 deletions(-)

diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
index 1f5b3dd31fcf..59fe157e5722 100644
--- a/drivers/virtio/virtio_balloon.c
+++ b/drivers/virtio/virtio_balloon.c
@@ -316,34 +316,48 @@ static inline void update_stat(struct virtio_balloon *vb, 
int idx,
#define pages_to_bytes(x) ((u64)(x) << PAGE_SHIFT) -static unsigned int update_balloon_stats(struct virtio_balloon *vb)
+/* Return the number of entries filled by vm events */
+static inline unsigned int update_balloon_vm_stats(struct virtio_balloon *vb,
+                                                  unsigned int start)
  {
+#ifdef CONFIG_VM_EVENT_COUNTERS
        unsigned long events[NR_VM_EVENT_ITEMS];
-       struct sysinfo i;
-       unsigned int idx = 0;
-       long available;
-       unsigned long caches;
+       unsigned int idx = start;
all_vm_events(events);
-       si_meminfo(&i);
-
-       available = si_mem_available();
-       caches = global_node_page_state(NR_FILE_PAGES);
-
-#ifdef CONFIG_VM_EVENT_COUNTERS
        update_stat(vb, idx++, VIRTIO_BALLOON_S_SWAP_IN,
-                               pages_to_bytes(events[PSWPIN]));
+                   pages_to_bytes(events[PSWPIN]));
        update_stat(vb, idx++, VIRTIO_BALLOON_S_SWAP_OUT,
-                               pages_to_bytes(events[PSWPOUT]));
+                   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
+#endif /* CONFIG_HUGETLB_PAGE */
+
+       return idx - start;
+#else /* CONFIG_VM_EVENT_COUNTERS */
+
+       return 0;
+#endif /* CONFIG_VM_EVENT_COUNTERS */
+}
+
+static unsigned int update_balloon_stats(struct virtio_balloon *vb)
+{
+       struct sysinfo i;
+       unsigned int idx = 0;
+       long available;
+       unsigned long caches;
+
+       idx += update_balloon_vm_stats(vb, idx);

No need to handle idx that complicated now. Just do

unsigned int idx;

idx = update_balloon_vm_stats(vb);

We can go down that path if we ever want to rearrange the code and not have the vm_stats first.

+
+       si_meminfo(&i);
+       available = si_mem_available();
+       caches = global_node_page_state(NR_FILE_PAGES);
        update_stat(vb, idx++, VIRTIO_BALLOON_S_MEMFREE,
                                pages_to_bytes(i.freeram));
        update_stat(vb, idx++, VIRTIO_BALLOON_S_MEMTOT,

--
Cheers,

David / dhildenb


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