On Mon, Jul 13, 2020 at 11:58 PM Guenter Roeck <linux@xxxxxxxxxxxx> wrote: > > On 7/13/20 11:05 PM, reg Kroah-Hartman wrote: > > On Mon, Jul 13, 2020 at 01:43:00PM -0700, Badhri Jagan Sridharan wrote: > >> "tReceiverResponse 15 ms Section 6.6.2 > >> The receiver of a Message requiring a response Shall respond > >> within tReceiverResponse in order to ensure that the > >> sender’s SenderResponseTimer does not expire." > >> > >> When the cpu complex is busy running other lower priority > >> work items, TCPM's work queue sometimes does not get scheduled > >> on time to meet the above requirement from the spec. > >> Elevating the TCPM's work queue to higher priority allows > >> TCPM to meet tReceiverResponse in a busy system. > >> > >> Signed-off-by: Badhri Jagan Sridharan <badhri@xxxxxxxxxx> > >> --- > >> drivers/usb/typec/tcpm/tcpm.c | 2 +- > >> 1 file changed, 1 insertion(+), 1 deletion(-) > >> > >> diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c > >> index 82b19ebd7838e0..088b6f1fa1ff89 100644 > >> --- a/drivers/usb/typec/tcpm/tcpm.c > >> +++ b/drivers/usb/typec/tcpm/tcpm.c > >> @@ -4747,7 +4747,7 @@ struct tcpm_port *tcpm_register_port(struct device *dev, struct tcpc_dev *tcpc) > >> mutex_init(&port->lock); > >> mutex_init(&port->swap_lock); > >> > >> - port->wq = create_singlethread_workqueue(dev_name(dev)); > >> + port->wq = alloc_ordered_workqueue("%s", WQ_HIGHPRI, dev_name(dev)); > > > > How are you "guaranteeing" that this is really going to change anything > > on a highly loaded machine? > > > > Yes, it might make things better, but if you have a hard deadline like > > this, you need to do things a bit differently to always ensure that you > > meet it. I do not think this change is that fix, do you? > > Yes Greg I agree with you, moving to HIGHPRI was making it better but is not going to solve the problem always. I was wondering whether are there better ways of doing this. > > Good point. The worker in drivers/watchdog/ !watchdog_dev.c might be > useful as a starting point. There may be better examples - this is > just one I know of which had a similar problem. See commits > 38a1222ae4f3 and 1ff688209e2e. > > Guenter Thanks a lot Guenter !! Very useful pointers, will review the approaches in both the commits !