Messages in this thread | | | From | Andy Lutomirski <> | Date | Fri, 16 Sep 2016 08:26:03 -0700 | Subject | Should drivers like nvme let userspace control their latency via dev_pm_qos? |
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I'm adding power management to the nvme driver, and I'm exposing exactly one knob via sysfs: the maximum permissible latency. This isn't a power domain issue, and it has no dependencies -- it's literally just the maximum latency that the driver may impose on I/O for power saving purposes.
ISTM userspace should be able to specify its own latency tolerance in a uniform way, and dev_pm_qos seems like the natural interface for this, except that I cannot find a single instance in the tree of *any* driver using it via the notifier mechanism. I can find two drivers that do it using dev_pm_qos_expose_latency_tolerance(), and both are LPSS drivers?
So: should I be exposing .set_latency_tolerance() or should I just use a custom sysfs attribute? Or both?
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