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lmkd: Detect the highest level of vmpressure when event is detected 

lmkd checks for vmpressure events using epoll_wait() with eventfds of
all registered events. It's possible that multiple events of different
priorities happen before epoll_wait() returns. For these cases we
use conservative approach by assuming that the system is under the
highest registered vmpressure levels. This speeds up lmkd response time
to high memory pressure by not responding to possibly stale low pressure
levels when vmpressure rises quickly.

Bug: 63631020
Test: alloc-stress

Change-Id: I79a85c3342e7e1b3a3be82945266b2cc60b437cf
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
This commit is contained in:
Suren Baghdasaryan 2018-01-04 09:16:21 -08:00
parent ceffaf2a37
commit 3e1a849c25
1 changed files with 14 additions and 5 deletions
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19
lmkd.c
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@ -102,7 +102,7 @@ static const char *level_name[] = {
}; };
static int level_oomadj[VMPRESS_LEVEL_COUNT]; static int level_oomadj[VMPRESS_LEVEL_COUNT];
static int mpevfd[VMPRESS_LEVEL_COUNT]; static int mpevfd[VMPRESS_LEVEL_COUNT] = { -1, -1, -1 };
static bool debug_process_killing; static bool debug_process_killing;
static bool enable_pressure_upgrade; static bool enable_pressure_upgrade;
static int64_t upgrade_pressure; static int64_t upgrade_pressure;
@ -745,11 +745,20 @@ static void mp_event_common(enum vmpressure_level level) {
unsigned long long evcount; unsigned long long evcount;
int64_t mem_usage, memsw_usage; int64_t mem_usage, memsw_usage;
int64_t mem_pressure; int64_t mem_pressure;
enum vmpressure_level lvl;
ret = read(mpevfd[level], &evcount, sizeof(evcount)); /*
if (ret < 0) * Check all event counters from low to critical
ALOGE("Error reading memory pressure event fd; errno=%d", * and upgrade to the highest priority one. By reading
errno); * eventfd we also reset the event counters.
*/
for (lvl = VMPRESS_LEVEL_LOW; lvl < VMPRESS_LEVEL_COUNT; lvl++) {
if (mpevfd[lvl] != -1 &&
read(mpevfd[lvl], &evcount, sizeof(evcount)) > 0 &&
evcount > 0 && lvl > level) {
level = lvl;
}
}
mem_usage = get_memory_usage(MEMCG_MEMORY_USAGE); mem_usage = get_memory_usage(MEMCG_MEMORY_USAGE);
memsw_usage = get_memory_usage(MEMCG_MEMORYSW_USAGE); memsw_usage = get_memory_usage(MEMCG_MEMORYSW_USAGE);