Messages in this thread | | | Subject | Re: [PATCH v5 00/11] serial: 8250: split LPSS to 8250_lpss, enable DMA on Quark | From | Bryan O'Donoghue <> | Date | Thu, 19 May 2016 02:18:53 +0100 |
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On Thu, 2016-05-12 at 18:06 +0300, Andy Shevchenko wrote: > On Fri, 2016-05-06 at 18:17 +0300, Andy Shevchenko wrote: > > This is combined series of two things: > > - split out the Intel LPSS specific driver from 8250_pci into > > 8250_lpss > > - enable DMA support on Intel Quark UART > > > > The patch has been tested on few Intel SoCs / platforms. In any > > case I > > would > > like to ask Bryan to do independent test.
Andy.
It looks as though there's a performance drop when enabling the DMA here (v) stock PIO mode with the 8250 driver.
Test setup Galileo Gen1 transmitter - Galileo Gen2 receiver. TX/RX cross-wired between the Arduino UART headers respectively (pins 0 & 1 on the "Digital PWM" header), GND pin14 similarly cross-wired.
User-space: Receiver: Stock on-flash yocto-tiny kernel 3.8.7 Transmitter: Galileo Debian image : https://sourceforge.net/projects/galileodebian/ 3.8.7 kernel: On SPI-flash BSP kernel andy-v4: From your tree d13ffcf ('serial: 8250: attempt to keep Kconfig and Makefile in order') tip-of-tree : 97f0090 ('Merge tag 'rproc-v4.7' of git://github.com/andersson/remoteproc')
Results:
### Test0 ###
galileo dma andy-v4 9600 8n1
root@galileo:~# time echo "abcdefghijklmnopqrstuvwxyz0123456789" > /dev/ttyS0
real 0m0.060s user 0m0.000s sys 0m0.000s
galileo non-dma Linux 3.8.7 9600 8n1:
9600 8n1 root@galileo:~# time echo "abcdefghijklmnopqrstuvwxyz0123456789" > /dev/ttyS0
real 0m0.051s user 0m0.000s sys 0m0.000s
galileo non-dma tip-of-tree 9600 8n1:
root@galileo:~# time echo "abcdefghijklmnopqrstuvwxyz0123456789" > /dev/ttyS0
real 0m0.048s user 0m0.000s sys 0m0.000s
### Test1 ###
galileo dma andy-v4 9600 8n1:
root@galileo:~# time echo "abcdefghijklmnopqrstuvwxyz0123456789abcdefghijklmnopqrstuvwxyz01234567 89abcdefghijklmnopqrstuvwxyz0123456789abcdefghijklmnopqrstuvwxyz0123456 789abcdefghijklmnopqrstuvwxyz0123456789" > /dev/ttyS0
real 0m0.209s user 0m0.000s sys 0m0.000s
galileo non-dma Linux 3.8.7 9600 8n1:
root@galileo:~# time echo "abcdefghijklmnopqrstuvwxyz0123456789abcdefghijklmnopqrstuvwxyz01234567 89abcdefghijklmnopqrstuvwxyz0123456789abcdefghijklmnopqrstuvwxyz0123456 789abcdefghijklmnopqrstuvwxyz0123456789" > /dev/ttyS0
real 0m0.206s user 0m0.000s sys 0m0.000s
galileo non-dma tip-of-tree 9600 8n1:
root@galileo:~# time echo "abcdefghijklmnopqrstuvwxyz0123456789abcdefghijklmnopqrstuvwxyz01234567 89abcdefghijklmnopqrstuvwxyz0123456789abcdefghijklmnopqrstuvwxyz0123456 789abcdefghijklmnopqrstuvwxyz0123456789" > /dev/ttyS0
real 0m0.199s user 0m0.010s sys 0m0.000s
--- bod
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