On Tue, 12/19 16:45, Peter Xu wrote:
> For each Monitor, add one field "use_io_thr" to show whether it will be
> using the dedicated monitor IO thread to handle input/output. When set,
> monitor IO parsing work will be offloaded to dedicated monitor IO
> thread, rather than the original main loop thread.
>
> This only works for QMP. HMP will always be run on main loop thread.
>
> Currently we're still keeping use_io_thr to off always. Will turn it on
> later at some point.
>
> One thing to mention is that we cannot set use_io_thr for every QMP
> monitors. The problem is that MUXed typed chardevs may not work well
> with it now. When MUX is used, frontend of chardev can be the monitor
> plus something else. The only thing we know would be safe to be run
> outside main thread so far is the monitor frontend. All the rest of the
> frontends should still be run in main thread only.
>
> Signed-off-by: Peter Xu <pet...@redhat.com>
> ---
> monitor.c | 41 ++++++++++++++++++++++++++++++++---------
> 1 file changed, 32 insertions(+), 9 deletions(-)
>
> diff --git a/monitor.c b/monitor.c
> index 4ebd83fd94..4b2bee773f 100644
> --- a/monitor.c
> +++ b/monitor.c
> @@ -190,6 +190,7 @@ struct Monitor {
> int flags;
> int suspend_cnt;
> bool skip_flush;
> + bool use_io_thr;
>
> QemuMutex out_lock;
> QString *outbuf;
> @@ -573,7 +574,8 @@ static void monitor_qapi_event_init(void)
>
> static void handle_hmp_command(Monitor *mon, const char *cmdline);
>
> -static void monitor_data_init(Monitor *mon, bool skip_flush)
> +static void monitor_data_init(Monitor *mon, bool skip_flush,
> + bool use_io_thr)
> {
> memset(mon, 0, sizeof(Monitor));
> qemu_mutex_init(&mon->out_lock);
> @@ -581,6 +583,7 @@ static void monitor_data_init(Monitor *mon, bool
> skip_flush)
> /* Use *mon_cmds by default. */
> mon->cmd_table = mon_cmds;
> mon->skip_flush = skip_flush;
> + mon->use_io_thr = use_io_thr;
> }
>
> static void monitor_data_destroy(Monitor *mon)
> @@ -601,7 +604,7 @@ char *qmp_human_monitor_command(const char *command_line,
> bool has_cpu_index,
> char *output = NULL;
> Monitor *old_mon, hmp;
>
> - monitor_data_init(&hmp, true);
> + monitor_data_init(&hmp, true, false);
>
> old_mon = cur_mon;
> cur_mon = &hmp;
> @@ -4103,8 +4106,9 @@ void error_vprintf_unless_qmp(const char *fmt, va_list
> ap)
> void monitor_init(Chardev *chr, int flags)
> {
> Monitor *mon = g_malloc(sizeof(*mon));
> + GMainContext *context;
>
> - monitor_data_init(mon, false);
> + monitor_data_init(mon, false, false);
>
> qemu_chr_fe_init(&mon->chr, chr, &error_abort);
> mon->flags = flags;
> @@ -4116,19 +4120,38 @@ void monitor_init(Chardev *chr, int flags)
> monitor_read_command(mon, 0);
> }
>
> + if (mon->use_io_thr) {
> + /*
> + * When use_io_thr is set, we use the global shared dedicated
> + * IO thread for this monitor to handle input/output.
> + */
> + context = monitor_io_context_get();
> + /* We should have inited globals before reaching here. */
> + assert(context);
> + } else {
> + /* The default main loop, which is the main thread */
> + context = NULL;
> + }
> +
> + /*
> + * Add the monitor before running it (which is triggered by
> + * qemu_chr_fe_set_handlers), otherwise one monitor may find
> + * itself not on the mon_list when running.
> + */
> + qemu_mutex_lock(&monitor_lock);
> + QTAILQ_INSERT_HEAD(&mon_list, mon, entry);
> + qemu_mutex_unlock(&monitor_lock);
> +
> if (monitor_is_qmp(mon)) {
> - qemu_chr_fe_set_handlers(&mon->chr, monitor_can_read,
> monitor_qmp_read,
> - monitor_qmp_event, NULL, mon, NULL, true);
> qemu_chr_fe_set_echo(&mon->chr, true);
> json_message_parser_init(&mon->qmp.parser, handle_qmp_command);
> + qemu_chr_fe_set_handlers(&mon->chr, monitor_can_read,
> monitor_qmp_read,
> + monitor_qmp_event, NULL, mon, context,
> true);
> } else {
> + assert(!context); /* HMP does not support IOThreads */
> qemu_chr_fe_set_handlers(&mon->chr, monitor_can_read, monitor_read,
> monitor_event, NULL, mon, NULL, true);
> }
> -
> - qemu_mutex_lock(&monitor_lock);
> - QLIST_INSERT_HEAD(&mon_list, mon, entry);
> - qemu_mutex_unlock(&monitor_lock);
> }
>
> void monitor_cleanup(void)
> --
> 2.14.3
>
Reviewed-by: Fam Zheng <f...@redhat.com>
