| Message ID | e957b4e7af8e1854e2a26e3f670c90687ed986a4.1340371865.git.quintela@redhat.com |
|---|---|
| State | New |
| Headers | show |
On 06/22/2012 04:46 PM, Juan Quintela wrote: > 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 <quintela@redhat.com> > --- > arch_init.c | 17 +++++++++++++++++ > 1 file changed, 17 insertions(+) > > diff --git a/arch_init.c b/arch_init.c > index 424efe7..7de1abf 100644 > --- a/arch_init.c > +++ b/arch_init.c > @@ -294,12 +294,15 @@ static void sort_ram_list(void) > g_free(blocks); > } > > +#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) { > memory_global_dirty_log_stop(); > @@ -339,6 +342,7 @@ 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; > > @@ -347,6 +351,19 @@ 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: %ld milliseconds, %d iterations\n", t1, i); > + break; > + } > + } > + i++; > } > > if (ret < 0) { Reviewed-by: Orit Wasserman <owasserm@redhat.com>
diff --git a/arch_init.c b/arch_init.c index 424efe7..7de1abf 100644 --- a/arch_init.c +++ b/arch_init.c @@ -294,12 +294,15 @@ static void sort_ram_list(void) g_free(blocks); } +#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) { memory_global_dirty_log_stop(); @@ -339,6 +342,7 @@ 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; @@ -347,6 +351,19 @@ 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: %ld milliseconds, %d iterations\n", t1, i); + break; + } + } + i++; } if (ret < 0) {
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 <quintela@redhat.com> --- arch_init.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+)