Messages in this thread | | | Subject | Re: [PATCH v1 3/3] drivers/tty: increase priority for tty_buffer_worker | From | Oleksij Rempel <> | Date | Mon, 28 Jan 2019 09:05:30 +0100 |
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On 10.01.19 17:30, Greg Kroah-Hartman wrote: > On Thu, Jan 10, 2019 at 04:19:53PM +0100, Oleksij Rempel wrote: >>> My gut feel is that if somebody still cares deeply about serial line >>> latency, they should look at trying to see if they can do some of the >>> work directly without the bounce to the workqueue. We use workqueues >>> for a reason, but it's possible that some of it could be avoided at >>> least in special cases... And yours sounds like a special case. >> >> It is for industrial low latency RS-422 based application. The loopback >> test is just easy way to test/reproduce it without additional hardware. >> >> What is good, mainlineable way to implement it? > > What is the real problem your systems are having? Are they serial-port > limited? Is latency a big issue? Trying to tune for a fake workload > isn't the best way to solve anything :)
The system in question is a high power laser cutter with live image-based inspection and adjustment of the cutting process. In this setup the RS422 interface is used to control parameters of the laser cutting unit in a tie control loop with the camera. This loops needs to operate at 1000 Hz.
The xy-stage moves with a speed of approx. 60m/min, i.e. within 1ms it moves about 1mm. For a high precision control process a jitter of ± 500 us (+/- 0.5mm) is unacceptable.
Kind regards, Oleksij Rempel
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