From e82e15c242d32272fe3493b0d358329e6e3d9fa7 Mon Sep 17 00:00:00 2001 From: Suren Baghdasaryan Date: Thu, 4 Jan 2018 09:16:21 -0800 Subject: [PATCH] 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 --- lmkd/lmkd.c | 19 ++++++++++++++----- 1 file changed, 14 insertions(+), 5 deletions(-) diff --git a/lmkd/lmkd.c b/lmkd/lmkd.c index 6def5f498..1b8fed378 100644 --- a/lmkd/lmkd.c +++ b/lmkd/lmkd.c @@ -102,7 +102,7 @@ static const char *level_name[] = { }; 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 enable_pressure_upgrade; static int64_t upgrade_pressure; @@ -745,11 +745,20 @@ static void mp_event_common(enum vmpressure_level level) { unsigned long long evcount; int64_t mem_usage, memsw_usage; int64_t mem_pressure; + enum vmpressure_level lvl; - ret = read(mpevfd[level], &evcount, sizeof(evcount)); - if (ret < 0) - ALOGE("Error reading memory pressure event fd; errno=%d", - errno); + /* + * Check all event counters from low to critical + * and upgrade to the highest priority one. By reading + * 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); memsw_usage = get_memory_usage(MEMCG_MEMORYSW_USAGE);