From 048c640a64fd064361382a8800de05c87ff630cb Mon Sep 17 00:00:00 2001 From: Dmitry Vyukov Date: Mon, 10 Jun 2024 11:10:14 +0200 Subject: executor: optimize waiting for child processes exit Currently we sleep only for 1 ms, which may produce some excessive CPU load (we usually have 6/8 such processes waiting). Make it sleep for 10 ms, but also make the sleep return immediately on child exit. This shuold both improve latency and reduce CPU load. --- executor/common.h | 2 +- executor/executor_bsd.h | 5 +++++ executor/executor_linux.h | 5 +++++ 3 files changed, 11 insertions(+), 1 deletion(-) (limited to 'executor') diff --git a/executor/common.h b/executor/common.h index fdbf4bcb1..3a735a086 100644 --- a/executor/common.h +++ b/executor/common.h @@ -678,9 +678,9 @@ static void loop(void) uint32 executed_calls = __atomic_load_n(output_data, __ATOMIC_RELAXED); #endif for (;;) { + sleep_ms(10); if (waitpid(-1, &status, WNOHANG | WAIT_FLAGS) == pid) break; - sleep_ms(1); #if SYZ_EXECUTOR // Even though the test process executes exit at the end // and execution time of each syscall is bounded by syscall_timeout_ms (~50ms), diff --git a/executor/executor_bsd.h b/executor/executor_bsd.h index 6c2174360..43c2a19a9 100644 --- a/executor/executor_bsd.h +++ b/executor/executor_bsd.h @@ -41,6 +41,11 @@ static void os_init(int argc, char** argv, void* data, size_t data_size) struct rlimit rlim; rlim.rlim_cur = rlim.rlim_max = kMaxFd; setrlimit(RLIMIT_NOFILE, &rlim); + + // A SIGCHLD handler makes sleep in loop exit immediately return with EINTR with a child exits. + struct sigaction act = {}; + act.sa_handler = [](int) {}; + sigaction(SIGCHLD, &act, nullptr); } static intptr_t execute_syscall(const call_t* c, intptr_t a[kMaxArgs]) diff --git a/executor/executor_linux.h b/executor/executor_linux.h index 3956127cd..bfd81776f 100644 --- a/executor/executor_linux.h +++ b/executor/executor_linux.h @@ -67,6 +67,11 @@ static void os_init(int argc, char** argv, char* data, size_t data_size) got = mmap(data + data_size, SYZ_PAGE_SIZE, PROT_NONE, MAP_ANON | MAP_PRIVATE | MAP_FIXED, -1, 0); if (data + data_size != got) failmsg("mmap of right data PROT_NONE page failed", "want %p, got %p", data + data_size, got); + + // A SIGCHLD handler makes sleep in loop exit immediately return with EINTR with a child exits. + struct sigaction act = {}; + act.sa_handler = [](int) {}; + sigaction(SIGCHLD, &act, nullptr); } static intptr_t execute_syscall(const call_t* c, intptr_t a[kMaxArgs]) -- cgit mrf-deployment