oomd: split swap and mem pressure event timers

One thing that came out of the test week is that systoomd needs to poll
more frequently so as not to race with the kernel oom killer in
situations where memory is eaten quickly. Memory pressure counters are
lagging so it isn't worthwhile to change the current read rate; however swap
is not lagging and can be checked more frequently.

So let's split these into 2 different timer events. As a result, swap
now also doesn't have to be subject to the post-action (post-kill) delay
that we need for memory pressure events.

Addresses some of slowness to kill discussed in
https://bugzilla.redhat.com/show_bug.cgi?id=1941340

1 files changed, 6 insertions, 3 deletions

diff --git a/src/oom/oomd-manager.h b/src/oom/oomd-manager.h
index 9c580c8a24..3df7ce94d7 100644
--- a/src/oom/oomd-manager.h
+++ b/src/oom/oomd-manager.h
@@ -7,7 +7,9 @@
 #include "varlink.h"
 
 /* Polling interval for monitoring stats */
-#define INTERVAL_USEC (1 * USEC_PER_SEC)
+#define SWAP_INTERVAL_USEC 150000 /* 0.15 seconds */
+/* Pressure counters are lagging (~2 seconds) compared to swap so polling too frequently just wastes CPU */
+#define MEM_PRESSURE_INTERVAL_USEC (1 * USEC_PER_SEC)
 
 /* Used to weight the averages */
 #define AVERAGE_SIZE_DECAY 4
@@ -45,9 +47,10 @@ struct Manager {
         OomdSystemContext system_context;
 
         usec_t last_reclaim_at;
-        usec_t post_action_delay_start;
+        usec_t mem_pressure_post_action_delay_start;
 
-        sd_event_source *cgroup_context_event_source;
+        sd_event_source *swap_context_event_source;
+        sd_event_source *mem_pressure_context_event_source;
 
         Varlink *varlink;
 };