Support reclaim with swappiness

Summary: https://lwn.net/Articles/956742/ We can now reclaim via: ``` echo 10M swappiness=0 > /sys/fs/cgroup/system.slice ``` Available on 6.4+ kernels Reviewed By: antonis-m Differential Revision: D57162912 fbshipit-source-id: d9ad3cd03f979b53a9f86e5349be9e036db79ee3
facebookincubator · May 10, 2024 · f78bcba · f78bcba
1 parent b2375be
commit f78bcba
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Showing 3 changed files with 24 additions and 3 deletions.
diff --git a/src/oomd/util/Fs.cpp b/src/oomd/util/Fs.cpp
@@ -756,8 +756,14 @@ SystemMaybe<Unit> Fs::writeMemhightmpAt(
   return noSystemError();
 }
 
-SystemMaybe<Unit> Fs::writeMemReclaimAt(const DirFd& dirfd, int64_t value) {
+SystemMaybe<Unit> Fs::writeMemReclaimAt(
+    const DirFd& dirfd,
+    int64_t value,
+    std::optional<int64_t> swappiness) {
   auto val_str = std::to_string(value);
+  if (swappiness) {
+    val_str += " swappiness=" + std::to_string(*swappiness);
+  }
   auto ret = writeControlFileAt(
       Fs::Fd::openat(dirfd, kMemReclaimFile, false), val_str);
   if (!ret) {

diff --git a/src/oomd/util/Fs.h b/src/oomd/util/Fs.h
@@ -231,7 +231,10 @@ class Fs {
       const DirFd& dirfd,
       int64_t value,
       std::chrono::microseconds duration);
-  static SystemMaybe<Unit> writeMemReclaimAt(const DirFd& dirfd, int64_t value);
+  static SystemMaybe<Unit> writeMemReclaimAt(
+      const DirFd& dirfd,
+      int64_t value,
+      std::optional<int64_t> swappiness);
 
   static SystemMaybe<int64_t> getNrDyingDescendantsAt(const DirFd& dirfd);
   static SystemMaybe<KillPreference> readKillPreferenceAt(const DirFd& path);

diff --git a/src/oomd/util/FsTest.cpp b/src/oomd/util/FsTest.cpp
@@ -477,12 +477,24 @@ TEST_F(FsTest, WriteMemoryReclaim) {
   F::materialize(F::makeDir(path, {F::makeFile("memory.reclaim")}));
 
   auto dir = ASSERT_SYS_OK(Fs::DirFd::open(path));
-  ASSERT_SYS_OK(Fs::writeMemReclaimAt(dir, 54321));
+  ASSERT_SYS_OK(Fs::writeMemReclaimAt(dir, 54321, std::nullopt));
   auto lines = ASSERT_SYS_OK(
       Fs::readFileByLine(Fs::Fd::openat(dir, Fs::kMemReclaimFile)));
   EXPECT_EQ(lines, std::vector{std::string("54321")});
 }
 
+TEST_F(FsTest, WriteMemoryReclaimWithSwappiness) {
+  using F = Fixture;
+  auto path = fixture_.cgroupDataDir() + "/write_test";
+  F::materialize(F::makeDir(path, {F::makeFile("memory.reclaim")}));
+
+  auto dir = ASSERT_SYS_OK(Fs::DirFd::open(path));
+  ASSERT_SYS_OK(Fs::writeMemReclaimAt(dir, 54321, 0));
+  auto lines = ASSERT_SYS_OK(
+      Fs::readFileByLine(Fs::Fd::openat(dir, Fs::kMemReclaimFile)));
+  EXPECT_EQ(lines, std::vector{std::string("54321 swappiness=0")});
+}
+
 TEST_F(FsTest, Swappiness) {
   using F = Fixture;
   auto path = fixture_.fsDataDir() + "/swappiness";