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2007-12-15
, 14:38
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Posts: 25 |
Thanked: 24 times |
Joined on Mar 2006
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#22
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2008-03-13
, 14:42
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Posts: 868 |
Thanked: 474 times |
Joined on Oct 2007
@ Capital District, NY, USA
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#23
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A while ago I looked for various kernel docs to see what's happening in the
wlan driver and what can be done to reduce cpu load. My impression was that
tasklet can be only preempted by hardware interrupts, so it is impossible to
sleep in it and give cpu resources to userland applications. If that is true,
no matter if n800 driver looks nicer, it must end up busylooping too.
Though on Nokia 770 cpu usage is attributed to the application doing (for
example wget) and on N800 it is attributed to 'OMAP McSPI/0' process.
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2008-03-13
, 22:25
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Posts: 55 |
Thanked: 6 times |
Joined on Feb 2008
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#24
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2008-03-13
, 22:55
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Posts: 868 |
Thanked: 474 times |
Joined on Oct 2007
@ Capital District, NY, USA
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#25
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2008-03-14
, 08:38
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Posts: 503 |
Thanked: 267 times |
Joined on Jul 2006
@ Helsinki
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#26
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Has there been any movement on the WiFi performance? Developer list said they have gotten the 770 up to 1.2mB/s download which would be 2 or 3 times the download performance I'm seeing on my 810 ( Usually 500kB/s over 802.11g ).
I've tried tuning the kernel, turning energy savings on and off, and many other tricks without any change. There is some other ceiling that I'm hitting and I have no idea where it is.
I think this is the problem has been discovered, but no word on if the n8x0 has actually gotten the patches to prevent network busylooping
https://garage.maemo.org/pipermail/c...ry/000012.html
So no matter how much I try in userland I will always be hamstring by bad programming in the kernel.
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2008-03-14
, 11:39
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Posts: 868 |
Thanked: 474 times |
Joined on Oct 2007
@ Capital District, NY, USA
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#27
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Performance depends on the way you are downloading data to the device. That ~1.2MB/s was measured as pure download speed, even without storing the received data on memory card. Saving data to memory card (that's natural for normal use) will drop the performance to ~1MB/s, using scp will decrease it even more because of extra load on cpu introduced by encryption. Poorly written download client may screw up the performance too. What have you used in your tests?
Some parts are closed, the glue between kernel and proprietary parts is open (mainly due to GPL requirements), see some details here http://garage.maemo.org/pipermail/cx...er/thread.html
As for cx3110x (the glue) - its quality is not exactly stellar, 770 version being much worse with CPU. For N800 version CPU consumption it the open part should be fine/better but it is hard to say without benchmarks. The wi-fi chip is connected over SPI bus, OMAP2 has SPI interface which handles SPI communication without needing much CPU, 770 uses McBSP chip (serial port) for SPI and busy-loops waiting for each result from the chip which eats a lot of CPU.
Newbies click here before posting. Thanks.
If you really need to PM me with troubleshooting question please consider posting it to the forum instead. It is OK to PM me a link to such post then. Thank you.