From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
To: Bryan O'Donoghue <pure.logic@nexus-software.ie>,
Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Peter Hurley <peter@hurleysoftware.com>,
"linux-serial@vger.kernel.org" <linux-serial@vger.kernel.org>,
Vinod Koul <vinod.koul@intel.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
dmaengine <dmaengine@vger.kernel.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
"Puustinen, Ismo" <ismo.puustinen@intel.com>,
Heikki Krogerus <heikki.krogerus@linux.intel.com>
Subject: Re: [PATCH v5 00/11] serial: 8250: split LPSS to 8250_lpss, enable DMA on Quark
Date: Mon, 13 Jun 2016 14:16:17 +0300 [thread overview]
Message-ID: <1465816577.30123.8.camel@linux.intel.com> (raw)
In-Reply-To: <1465751587.15050.23.camel@nexus-software.ie>
On Sun, 2016-06-12 at 18:13 +0100, Bryan O'Donoghue wrote:
> On Tue, 2016-06-07 at 13:04 +0300, Andy Shevchenko wrote:
> > > I'll find some time to look at both a short stream and a long
> > stream,
> > > based on the branch you've indicated and maybe against the latest
> > > stable kernel.
> >
> > Please, do. I'm planning to resend new version soon (this week or
> > lately beginning of the next one).
>
> So.
>
> Generally DMA appears to make little-to-no difference here.
Yes, because your test shows the speed of the serial data line.
What we are trying to measure here?
If you would like to measure CPU load it will require threaded
application and some load task to see the difference. Another metric
which may help is interrupt counters. I'm wondering if perf can help
here as well.
> One thing I have noticed is that the following never completes and
> can't be reset back to mode=0 or mode=3 to restore functionality -
> definitely worth looking at if you are spinning another patch.
>
> ### never completes ####
> root@galileo:~# echo 1 > /sys/class/tty/ttyS0/dma_mode
> root@galileo:~# stty -F /dev/ttyS0 921600
> root@galileo:~# time cat tester.txt > /dev/ttyS0
> ### never completes ####
Thanks for that test, I will try to reproduce on my side.
--
Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Intel Finland Oy
next prev parent reply other threads:[~2016-06-13 11:16 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-05-06 15:17 [PATCH v5 00/11] serial: 8250: split LPSS to 8250_lpss, enable DMA on Quark Andy Shevchenko
2016-05-06 15:17 ` [PATCH v5 01/11] dmaengine: dw: keep copy of custom slave config in dwc Andy Shevchenko
2016-05-06 15:17 ` [PATCH v5 02/11] dmaengine: dw: provide probe(), remove() stubs for users Andy Shevchenko
2016-05-06 15:17 ` [PATCH v5 03/11] dmaengine: dw: set polarity of handshake interface Andy Shevchenko
2016-05-06 15:17 ` [PATCH v5 04/11] dmaengine: dw: override LLP support if asked in platform data Andy Shevchenko
2016-05-06 15:17 ` [PATCH v5 05/11] serial: 8250_dma: switch to new dmaengine_terminate_* API Andy Shevchenko
2016-05-06 15:17 ` [PATCH v5 06/11] serial: 8250_dma: adjust DMA address of the UART Andy Shevchenko
2016-05-06 15:17 ` [PATCH v5 07/11] serial: 8250: enable AFE on ports where FIFO is 16 bytes Andy Shevchenko
2016-05-06 15:17 ` [PATCH v5 08/11] serial: 8250_lpss: split LPSS driver to separate module Andy Shevchenko
2016-05-06 15:17 ` [PATCH v5 09/11] serial: 8250_lpss: move Quark code from PCI driver Andy Shevchenko
2016-05-06 15:17 ` [PATCH v5 10/11] serial: 8250_lpss: enable MSI for Intel Quark Andy Shevchenko
2016-05-06 15:17 ` [PATCH v5 11/11] serial: 8250_lpss: enable DMA on Intel Quark UART Andy Shevchenko
2016-05-12 15:06 ` [PATCH v5 00/11] serial: 8250: split LPSS to 8250_lpss, enable DMA on Quark Andy Shevchenko
2016-05-12 15:59 ` Vinod Koul
2016-05-19 1:18 ` Bryan O'Donoghue
2016-05-24 17:37 ` Andy Shevchenko
2016-05-24 18:08 ` Andy Shevchenko
2016-05-26 16:36 ` Bryan O'Donoghue
2016-06-07 10:04 ` Andy Shevchenko
2016-06-12 17:13 ` Bryan O'Donoghue
2016-06-13 11:16 ` Andy Shevchenko [this message]
2016-05-26 16:11 ` Bryan O'Donoghue
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