Re: [PATCH 0/2] net: davinci_cpdma: reduce latency on -rt
From: Uwe Kleine-König <hidden>
Date: 2016-07-27 14:38:10
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linux-omap
Hello, On Wed, Jul 27, 2016 at 05:11:54PM +0300, Grygorii Strashko wrote:
On 07/27/2016 10:03 AM, Uwe Kleine-König wrote:quoted
On Tue, Jul 26, 2016 at 05:36:49PM +0300, Grygorii Strashko wrote:quoted
On 07/26/2016 03:02 PM, Uwe Kleine-König wrote:quoted
Hello, these patches are based on next-20160726. I didn't check yet how latency improves by using these patches, but even if the improvment is small, it's still a good idea to have them.Sry, but how this will affect on -RT? This is not a raw locks, so they will be converted to rt-mutexes which are sleepable. Or I've missed smth?They are still locks after all. On -rt I saw for the relevant application: send package | take lock | write pckt to hw | | rcv irq | take lock | schedule drop lock | schedule | | get pckt from hw | drop lock So reducing the time a lock is taken reduces the chances that the lock is contended for another thread which results in extra context switches.Thanks a lot for explanation. So, this is not exactly rt-latency reduction, but it might improve net performance on -RT. correct?
Well, it's not really rt related, but if you hit a locked lock on rt it hurts more than on !rt. And this results in increased latency. Best regards Uwe -- Pengutronix e.K. | Uwe Kleine-König | Industrial Linux Solutions | http://www.pengutronix.de/ |