From mboxrd@z Thu Jan 1 00:00:00 1970 From: Uwe =?iso-8859-1?Q?Kleine-K=F6nig?= Subject: Re: [PATCH 0/2] net: davinci_cpdma: reduce latency on -rt Date: Wed, 27 Jul 2016 09:03:02 +0200 Message-ID: <20160727070302.GG5368@pengutronix.de> References: <1469534545-14478-1-git-send-email-u.kleine-koenig@pengutronix.de> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: Mugunthan V N , linux-omap@vger.kernel.org, netdev@vger.kernel.org, kernel@pengutronix.de To: Grygorii Strashko Return-path: Received: from metis.ext.4.pengutronix.de ([92.198.50.35]:39944 "EHLO metis.ext.4.pengutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751504AbcG0HDH (ORCPT ); Wed, 27 Jul 2016 03:03:07 -0400 Content-Disposition: inline In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: On Tue, Jul 26, 2016 at 05:36:49PM +0300, Grygorii Strashko wrote: > On 07/26/2016 03:02 PM, Uwe Kleine-K=F6nig wrote: > >Hello, > > > >these patches are based on next-20160726. I didn't check yet how lat= ency > >improves by using these patches, but even if the improvment is small= , > >it's still a good idea to have them. >=20 > 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 |=20 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= =2E Best regards Uwe --=20 Pengutronix e.K. | Uwe Kleine-K=F6nig = | Industrial Linux Solutions | http://www.pengutronix.de/= |