From: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
To: Grygorii Strashko <grygorii.strashko@ti.com>
Cc: Mugunthan V N <mugunthanvnm@ti.com>,
linux-omap@vger.kernel.org, netdev@vger.kernel.org,
kernel@pengutronix.de
Subject: Re: [PATCH 0/2] net: davinci_cpdma: reduce latency on -rt
Date: Wed, 27 Jul 2016 16:38:04 +0200 [thread overview]
Message-ID: <20160727143804.GC5629@pengutronix.de> (raw)
In-Reply-To: <076e6aa6-91f3-8707-1d8b-504c4962f7cd@ti.com>
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:
> > On Tue, Jul 26, 2016 at 05:36:49PM +0300, Grygorii Strashko wrote:
> >> On 07/26/2016 03:02 PM, Uwe Kleine-König wrote:
> >>> 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/ |
next prev parent reply other threads:[~2016-07-27 14:38 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-07-26 12:02 [PATCH 0/2] net: davinci_cpdma: reduce latency on -rt Uwe Kleine-König
2016-07-26 12:02 ` [PATCH 1/2] net: davinci_cpdma: reduce time holding ctlr->lock in cpdma_control_set Uwe Kleine-König
2016-08-04 15:22 ` Grygorii Strashko
2016-08-09 8:27 ` Mugunthan V N
2016-07-26 12:02 ` [PATCH 2/2] net: davinci_cpdma: reduce time holding chan->lock in cpdma_chan_submit Uwe Kleine-König
2016-07-26 14:25 ` Grygorii Strashko
2016-07-27 7:12 ` Uwe Kleine-König
2016-07-27 14:08 ` Grygorii Strashko
2016-07-27 18:11 ` Ivan Khoronzhuk
2016-07-26 14:36 ` [PATCH 0/2] net: davinci_cpdma: reduce latency on -rt Grygorii Strashko
2016-07-27 7:03 ` Uwe Kleine-König
2016-07-27 14:11 ` Grygorii Strashko
2016-07-27 14:38 ` Uwe Kleine-König [this message]
2016-07-28 9:34 ` Grygorii Strashko
2016-07-28 12:12 ` Uwe Kleine-König
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