diff options
| -rw-r--r-- | main-loop.c | 25 |
1 files changed, 25 insertions, 0 deletions
diff --git a/main-loop.c b/main-loop.c index eb80ff369f..f46aece8b8 100644 --- a/main-loop.c +++ b/main-loop.c @@ -188,14 +188,39 @@ static void glib_pollfds_poll(void) } } +#define MAX_MAIN_LOOP_SPIN (1000) + static int os_host_main_loop_wait(uint32_t timeout) { int ret; + static int spin_counter; glib_pollfds_fill(&timeout); + /* If the I/O thread is very busy or we are incorrectly busy waiting in + * the I/O thread, this can lead to starvation of the BQL such that the + * VCPU threads never run. To make sure we can detect the later case, + * print a message to the screen. If we run into this condition, create + * a fake timeout in order to give the VCPU threads a chance to run. + */ + if (spin_counter > MAX_MAIN_LOOP_SPIN) { + static bool notified; + + if (!notified) { + fprintf(stderr, + "main-loop: WARNING: I/O thread spun for %d iterations\n", + MAX_MAIN_LOOP_SPIN); + notified = true; + } + + timeout = 1; + } + if (timeout > 0) { + spin_counter = 0; qemu_mutex_unlock_iothread(); + } else { + spin_counter++; } ret = g_poll((GPollFD *)gpollfds->data, gpollfds->len, timeout); |