lkml.org 
[lkml]   [2019]   [Jan]   [28]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH v1 3/3] drivers/tty: increase priority for tty_buffer_worker
From
Date


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

--
Pengutronix e.K. | |
Industrial Linux Solutions | http://www.pengutronix.de/ |
Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 |
Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |

\
 
 \ /
  Last update: 2019-01-28 09:07    [W:0.159 / U:0.700 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site