Messages in this thread | | | Date | Thu, 17 Dec 2020 10:21:20 -0800 | From | rishabhb@codeauro ... | Subject | Re: [PATCH] remoteproc: Create a separate workqueue for recovery tasks |
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On 2020-12-17 08:12, Alex Elder wrote: > On 12/15/20 4:55 PM, Bjorn Andersson wrote: >> On Sat 12 Dec 14:48 CST 2020, Rishabh Bhatnagar wrote: >> >>> Create an unbound high priority workqueue for recovery tasks. > > I have been looking at a different issue that is caused by > crash notification. > > What happened was that the modem crashed while the AP was > in system suspend (or possibly even resuming) state. And > there is no guarantee that the system will have called a > driver's ->resume callback when the crash notification is > delivered. > > In my case (in the IPA driver), handling a modem crash > cannot be done while the driver is suspended; i.e. the > activities in its ->resume callback must be completed > before we can recover from the crash. > > For this reason I might like to change the way the > crash notification is handled, but what I'd rather see > is to have the work queue not run until user space > is unfrozen, which would guarantee that all drivers > that have registered for a crash notification will > be resumed when the notification arrives. > > I'm not sure how that interacts with what you are > looking for here. I think the workqueue could still > be unbound, but its work would be delayed longer before > any notification (and recovery) started. > > -Alex > > In that case, maybe adding a "WQ_FREEZABLE" flag might help? > >> This simply repeats $subject >> >>> Recovery time is an important parameter for a subsystem and there >>> might be situations where multiple subsystems crash around the same >>> time. Scheduling into an unbound workqueue increases parallelization >>> and avoids time impact. >> >> You should be able to write this more succinctly. The important part >> is >> that you want an unbound work queue to allow recovery to happen in >> parallel - which naturally implies that you care about recovery >> latency. >> >>> Also creating a high priority workqueue >>> will utilize separate worker threads with higher nice values than >>> normal ones. >>> >> >> This doesn't describe why you need the higher priority. >> >> >> I believe, and certainly with the in-line coredump, that we're running >> our recovery work for way too long to be queued on the system_wq. As >> such the content of the patch looks good! >> >> Regards, >> Bjorn >> >>> Signed-off-by: Rishabh Bhatnagar <rishabhb@codeaurora.org> >>> --- >>> drivers/remoteproc/remoteproc_core.c | 9 ++++++++- >>> 1 file changed, 8 insertions(+), 1 deletion(-) >>> >>> diff --git a/drivers/remoteproc/remoteproc_core.c >>> b/drivers/remoteproc/remoteproc_core.c >>> index 46c2937..8fd8166 100644 >>> --- a/drivers/remoteproc/remoteproc_core.c >>> +++ b/drivers/remoteproc/remoteproc_core.c >>> @@ -48,6 +48,8 @@ static DEFINE_MUTEX(rproc_list_mutex); >>> static LIST_HEAD(rproc_list); >>> static struct notifier_block rproc_panic_nb; >>> +static struct workqueue_struct *rproc_wq; >>> + >>> typedef int (*rproc_handle_resource_t)(struct rproc *rproc, >>> void *, int offset, int avail); >>> @@ -2475,7 +2477,7 @@ void rproc_report_crash(struct rproc *rproc, >>> enum rproc_crash_type type) >>> rproc->name, rproc_crash_to_string(type)); >>> /* create a new task to handle the error */ >>> - schedule_work(&rproc->crash_handler); >>> + queue_work(rproc_wq, &rproc->crash_handler); >>> } >>> EXPORT_SYMBOL(rproc_report_crash); >>> @@ -2520,6 +2522,10 @@ static void __exit rproc_exit_panic(void) >>> static int __init remoteproc_init(void) >>> { >>> + rproc_wq = alloc_workqueue("rproc_wq", WQ_UNBOUND | WQ_HIGHPRI, 0); >>> + if (!rproc_wq) >>> + return -ENOMEM; >>> + >>> rproc_init_sysfs(); >>> rproc_init_debugfs(); >>> rproc_init_cdev(); >>> @@ -2536,6 +2542,7 @@ static void __exit remoteproc_exit(void) >>> rproc_exit_panic(); >>> rproc_exit_debugfs(); >>> rproc_exit_sysfs(); >>> + destroy_workqueue(rproc_wq); >>> } >>> module_exit(remoteproc_exit); >>> -- The Qualcomm Innovation Center, Inc. is a member of the Code >>> Aurora Forum, >>> a Linux Foundation Collaborative Project >>>
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