Cc'ing the chardev maintainers.
On 11/22/19 10:23 AM, Yury Kotov wrote:
The monitor_can_read (as a callback of qemu_chr_fe_set_handlers)
should return size of buffer which monitor_qmp_read or monitor_read
can process.
Currently, monitor_can_read returns 1 as a result of logical not.
Thus, for each QMP command, len(QMD) iterations of the main loop
are required to handle a command.
In fact, these both functions can process any buffer size.
So, return 1024 as a reasonable size which is enough to process
the most QMP commands, but not too big to block the main loop for
a long time.
Signed-off-by: Yury Kotov <yury-ko...@yandex-team.ru>
---
monitor/monitor.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/monitor/monitor.c b/monitor/monitor.c
index 12898b6448..cac3f39727 100644
--- a/monitor/monitor.c
+++ b/monitor/monitor.c
@@ -50,6 +50,13 @@ typedef struct {
int64_t rate; /* Minimum time (in ns) between two events */
} MonitorQAPIEventConf;
+/*
+ * The maximum buffer size which the monitor can process in one iteration
+ * of the main loop. We don't want to block the loop for a long time
+ * because of JSON parser, so use a reasonable value.
+ */
+#define MONITOR_READ_LEN_MAX 1024
This looks reasonable.
Reviewed-by: Philippe Mathieu-Daudé <phi...@redhat.com>
+
/* Shared monitor I/O thread */
IOThread *mon_iothread;
@@ -498,7 +505,7 @@ int monitor_can_read(void *opaque)
{
Monitor *mon = opaque;
- return !atomic_mb_read(&mon->suspend_cnt);
+ return atomic_mb_read(&mon->suspend_cnt) ? 0 : MONITOR_READ_LEN_MAX;
}
void monitor_list_append(Monitor *mon)
