feat: support linux v6.12 balloon stat

When the guest runs a kernel >= v6.12, the balloon stats API
will not crash and will return additional metrics: oom_kill,
alloc_stall, async_scan, direct_scan, async_reclaim, direct_reclaim

these metrics can be found in the related kernel commit:
74c025c5d7e4ac7c7ad269c1ee64da4bdfe4770c

To avoid any misunderstanding, these metrics are omitted when
the guest kernel < v6.12.

Signed-off-by: 刘顺钰 <[email protected]>

Author: laushunyu

CHANGELOG.md

@@ -19,6 +19,9 @@ and this project adheres to
 - [#4028](https://github.com/firecracker-microvm/firecracker/pull/4028):
   Firecracker now creates the log and metrics files if they do not exist,
   simplifying the launch of Firecracker by removing a manual step.
+- [#5516](https://github.com/firecracker-microvm/firecracker/pull/5516): Balloon
+  stat now supports guest kernel >= 6.12. Now we have a metric to analyze the
+  memory performance.
 
 ### Deprecated
 

src/vmm/src/devices/virtio/balloon/device.rs

@@ -19,9 +19,11 @@ use super::{
     BALLOON_DEV_ID, BALLOON_NUM_QUEUES, BALLOON_QUEUE_SIZES, DEFLATE_INDEX, INFLATE_INDEX,
     MAX_PAGE_COMPACT_BUFFER, MAX_PAGES_IN_DESC, MIB_TO_4K_PAGES, STATS_INDEX,
     VIRTIO_BALLOON_F_DEFLATE_ON_OOM, VIRTIO_BALLOON_F_STATS_VQ, VIRTIO_BALLOON_PFN_SHIFT,
-    VIRTIO_BALLOON_S_AVAIL, VIRTIO_BALLOON_S_CACHES, VIRTIO_BALLOON_S_HTLB_PGALLOC,
-    VIRTIO_BALLOON_S_HTLB_PGFAIL, VIRTIO_BALLOON_S_MAJFLT, VIRTIO_BALLOON_S_MEMFREE,
-    VIRTIO_BALLOON_S_MEMTOT, VIRTIO_BALLOON_S_MINFLT, VIRTIO_BALLOON_S_SWAP_IN,
+    VIRTIO_BALLOON_S_ALLOC_STALL, VIRTIO_BALLOON_S_ASYNC_RECLAIM, VIRTIO_BALLOON_S_ASYNC_SCAN,
+    VIRTIO_BALLOON_S_AVAIL, VIRTIO_BALLOON_S_CACHES, VIRTIO_BALLOON_S_DIRECT_RECLAIM,
+    VIRTIO_BALLOON_S_DIRECT_SCAN, VIRTIO_BALLOON_S_HTLB_PGALLOC, VIRTIO_BALLOON_S_HTLB_PGFAIL,
+    VIRTIO_BALLOON_S_MAJFLT, VIRTIO_BALLOON_S_MEMFREE, VIRTIO_BALLOON_S_MEMTOT,
+    VIRTIO_BALLOON_S_MINFLT, VIRTIO_BALLOON_S_OOM_KILL, VIRTIO_BALLOON_S_SWAP_IN,
     VIRTIO_BALLOON_S_SWAP_OUT,
 };
 use crate::devices::virtio::balloon::BalloonError;
@@ -133,6 +135,24 @@ pub struct BalloonStats {
     /// in the guest.
     #[serde(skip_serializing_if = "Option::is_none")]
     pub hugetlb_failures: Option<u64>,
+    /// OOM killer invocations. since linux v6.12.
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub oom_kill: Option<u64>,
+    /// Stall count of memory allocatoin. since linux v6.12.
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub alloc_stall: Option<u64>,
+    /// Amount of memory scanned asynchronously. since linux v6.12.
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub async_scan: Option<u64>,
+    /// Amount of memory scanned directly. since linux v6.12.
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub direct_scan: Option<u64>,
+    /// Amount of memory reclaimed asynchronously. since linux v6.12.
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub async_reclaim: Option<u64>,
+    /// Amount of memory reclaimed directly. since linux v6.12.
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub direct_reclaim: Option<u64>,
 }
 
 impl BalloonStats {
@@ -149,6 +169,12 @@ impl BalloonStats {
             VIRTIO_BALLOON_S_CACHES => self.disk_caches = val,
             VIRTIO_BALLOON_S_HTLB_PGALLOC => self.hugetlb_allocations = val,
             VIRTIO_BALLOON_S_HTLB_PGFAIL => self.hugetlb_failures = val,
+            VIRTIO_BALLOON_S_OOM_KILL => self.oom_kill = val,
+            VIRTIO_BALLOON_S_ALLOC_STALL => self.alloc_stall = val,
+            VIRTIO_BALLOON_S_ASYNC_SCAN => self.async_scan = val,
+            VIRTIO_BALLOON_S_DIRECT_SCAN => self.direct_scan = val,
+            VIRTIO_BALLOON_S_ASYNC_RECLAIM => self.async_reclaim = val,
+            VIRTIO_BALLOON_S_DIRECT_RECLAIM => self.direct_reclaim = val,
             _ => {
                 return Err(BalloonError::MalformedPayload);
             }
@@ -694,6 +720,12 @@ pub(crate) mod tests {
             disk_caches: Some(0),
             hugetlb_allocations: Some(0),
             hugetlb_failures: Some(0),
+            oom_kill: None,
+            alloc_stall: None,
+            async_scan: None,
+            direct_scan: None,
+            async_reclaim: None,
+            direct_reclaim: None,
         };
 
         let mut stat = BalloonStat {
@@ -730,6 +762,24 @@ pub(crate) mod tests {
         stat.tag = VIRTIO_BALLOON_S_HTLB_PGFAIL;
         stats.update_with_stat(&stat).unwrap();
         assert_eq!(stats.hugetlb_failures, Some(1));
+        stat.tag = VIRTIO_BALLOON_S_OOM_KILL;
+        stats.update_with_stat(&stat).unwrap();
+        assert_eq!(stats.oom_kill, Some(1));
+        stat.tag = VIRTIO_BALLOON_S_ALLOC_STALL;
+        stats.update_with_stat(&stat).unwrap();
+        assert_eq!(stats.alloc_stall, Some(1));
+        stat.tag = VIRTIO_BALLOON_S_ASYNC_SCAN;
+        stats.update_with_stat(&stat).unwrap();
+        assert_eq!(stats.async_scan, Some(1));
+        stat.tag = VIRTIO_BALLOON_S_DIRECT_SCAN;
+        stats.update_with_stat(&stat).unwrap();
+        assert_eq!(stats.direct_scan, Some(1));
+        stat.tag = VIRTIO_BALLOON_S_ASYNC_RECLAIM;
+        stats.update_with_stat(&stat).unwrap();
+        assert_eq!(stats.async_reclaim, Some(1));
+        stat.tag = VIRTIO_BALLOON_S_DIRECT_RECLAIM;
+        stats.update_with_stat(&stat).unwrap();
+        assert_eq!(stats.direct_reclaim, Some(1));
     }
 
     #[test]

src/vmm/src/devices/virtio/balloon/mod.rs

@@ -53,7 +53,7 @@ pub const STATS_INDEX: usize = 2;
 const VIRTIO_BALLOON_F_STATS_VQ: u32 = 1; // Enable statistics.
 const VIRTIO_BALLOON_F_DEFLATE_ON_OOM: u32 = 2; // Deflate balloon on OOM.
 
-// The statistics tags.
+// The statistics tags. defined in linux "include/uapi/linux/virtio_balloon.h".
 const VIRTIO_BALLOON_S_SWAP_IN: u16 = 0;
 const VIRTIO_BALLOON_S_SWAP_OUT: u16 = 1;
 const VIRTIO_BALLOON_S_MAJFLT: u16 = 2;
@@ -64,6 +64,12 @@ const VIRTIO_BALLOON_S_AVAIL: u16 = 6;
 const VIRTIO_BALLOON_S_CACHES: u16 = 7;
 const VIRTIO_BALLOON_S_HTLB_PGALLOC: u16 = 8;
 const VIRTIO_BALLOON_S_HTLB_PGFAIL: u16 = 9;
+const VIRTIO_BALLOON_S_OOM_KILL: u16 = 10;
+const VIRTIO_BALLOON_S_ALLOC_STALL: u16 = 11;
+const VIRTIO_BALLOON_S_ASYNC_SCAN: u16 = 12;
+const VIRTIO_BALLOON_S_DIRECT_SCAN: u16 = 13;
+const VIRTIO_BALLOON_S_ASYNC_RECLAIM: u16 = 14;
+const VIRTIO_BALLOON_S_DIRECT_RECLAIM: u16 = 15;
 
 /// Balloon device related errors.
 #[derive(Debug, thiserror::Error, displaydoc::Display)]

src/vmm/src/devices/virtio/balloon/persist.rs

@@ -41,6 +41,12 @@ pub struct BalloonStatsState {
     disk_caches: Option<u64>,
     hugetlb_allocations: Option<u64>,
     hugetlb_failures: Option<u64>,
+    oom_kill: Option<u64>,
+    alloc_stall: Option<u64>,
+    async_scan: Option<u64>,
+    direct_scan: Option<u64>,
+    async_reclaim: Option<u64>,
+    direct_reclaim: Option<u64>,
 }
 
 impl BalloonStatsState {
@@ -56,6 +62,12 @@ impl BalloonStatsState {
             disk_caches: stats.disk_caches,
             hugetlb_allocations: stats.hugetlb_allocations,
             hugetlb_failures: stats.hugetlb_failures,
+            oom_kill: stats.oom_kill,
+            alloc_stall: stats.alloc_stall,
+            async_scan: stats.async_scan,
+            direct_scan: stats.direct_scan,
+            async_reclaim: stats.async_reclaim,
+            direct_reclaim: stats.direct_reclaim,
         }
     }
 
@@ -75,6 +87,12 @@ impl BalloonStatsState {
             disk_caches: self.disk_caches,
             hugetlb_allocations: self.hugetlb_allocations,
             hugetlb_failures: self.hugetlb_failures,
+            oom_kill: self.oom_kill,
+            alloc_stall: self.alloc_stall,
+            async_scan: self.async_scan,
+            direct_scan: self.direct_scan,
+            async_reclaim: self.async_reclaim,
+            direct_reclaim: self.direct_reclaim,
         }
     }
 }
@@ -166,7 +184,6 @@ impl Persist<'_> for Balloon {
 
 #[cfg(test)]
 mod tests {
-
     use super::*;
     use crate::devices::virtio::device::VirtioDevice;
     use crate::devices::virtio::test_utils::{default_interrupt, default_mem};