From 4508bd9ed8053cef0a1a849bf2f1896a5dd86580 Mon Sep 17 00:00:00 2001 From: Juan Quintela Date: Tue, 22 May 2012 16:27:59 +0200 Subject: [PATCH] Exit loop if we have been there too long Checking each 64 pages is a random magic number as good as any other. We don't want to test too many times, but on the other hand, qemu_get_clock_ns() is not so expensive either. We want to be sure that we spent less than 50ms (half of buffered_file timer), if we spent more than 100ms, all the accounting got wrong. Signed-off-by: Juan Quintela --- arch_init.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) diff --git a/arch_init.c b/arch_init.c index 3633f4c0a6..64b85fd1b1 100644 --- a/arch_init.c +++ b/arch_init.c @@ -309,12 +309,15 @@ static void migration_end(void) memory_global_dirty_log_stop(); } +#define MAX_WAIT 50 /* ms, half buffered_file limit */ + int ram_save_live(QEMUFile *f, int stage, void *opaque) { ram_addr_t addr; uint64_t bytes_transferred_last; double bwidth = 0; int ret; + int i; if (stage < 0) { migration_end(); @@ -354,6 +357,7 @@ int ram_save_live(QEMUFile *f, int stage, void *opaque) bytes_transferred_last = bytes_transferred; bwidth = qemu_get_clock_ns(rt_clock); + i = 0; while ((ret = qemu_file_rate_limit(f)) == 0) { int bytes_sent; @@ -362,6 +366,20 @@ int ram_save_live(QEMUFile *f, int stage, void *opaque) if (bytes_sent == 0) { /* no more blocks */ break; } + /* we want to check in the 1st loop, just in case it was the 1st time + and we had to sync the dirty bitmap. + qemu_get_clock_ns() is a bit expensive, so we only check each some + iterations + */ + if ((i & 63) == 0) { + uint64_t t1 = (qemu_get_clock_ns(rt_clock) - bwidth) / 1000000; + if (t1 > MAX_WAIT) { + DPRINTF("big wait: " PRIu64 " milliseconds, %d iterations\n", + t1, i); + break; + } + } + i++; } if (ret < 0) {