buildkite: deflake itimer test

The self-admittedly arbitrary threshold of 20% of alarms being sent to the main
thread was being breached. I saw a run of of ~20-23% [1]. We should allow for a
little more breathing room.

1 - https://buildkite.com/gvisor/pipeline/builds/7400

PiperOrigin-RevId: 386503482

1 files changed, 4 insertions, 3 deletions

diff --git a/test/syscalls/linux/itimer.cc b/test/syscalls/linux/itimer.cc
index ac113e6da..9fb04eae6 100644
--- a/test/syscalls/linux/itimer.cc
+++ b/test/syscalls/linux/itimer.cc
@@ -197,9 +197,9 @@ int TestSIGALRMToMainThread() {
   // (but don't guarantee it), so we expect to see most samples on the main
   // thread.
   //
-  // The number of SIGALRMs delivered to a worker should not exceed 20%
+  // The number of SIGALRMs delivered to a worker should not exceed 40%
   // of the number of total signals expected (this is somewhat arbitrary).
-  const int worker_threshold = result.expected_total / 5;
+  const int worker_threshold = result.expected_total / 5 * 2;
 
   //
   // Linux only guarantees timers will never expire before the requested time.
@@ -230,7 +230,8 @@ TEST(ItimerTest, DeliversSIGALRMToMainThread) {
   // Not required anymore.
   kill.Release();
 
-  EXPECT_TRUE(WIFEXITED(status) && WEXITSTATUS(status) == 0) << status;
+  EXPECT_EQ(WIFEXITED(status) && WEXITSTATUS(status), 0)
+      << WIFEXITED(status) << " " << WEXITSTATUS(status);
 }
 
 // Signals are delivered to threads fairly.