WLAN with Linux SDIO: sneak preview
Werner Almesberger
werner at openmoko.org
Mon Nov 3 08:05:57 CET 2008
Wolfgang Spraul wrote:
> "Above all, abandonment is the key to innovation
Heh, I found one, too. An unlikely source, but right on the mark:
"The first step to improvement, whether mental, moral, or religious,
is to know ourselves - our weakness, errors, deficiencies, and sins,
that, by divine grace, we may overcome and turn from them all"
-- Tryon Edwards (American Theologian, 1809-1894)
Now, with stable-tracking fixed again, we can learn a bit more about
the weaknesses and deficiencies of our stacks. I redid the measurement
with the Linux stack as well, because the missing drivers may have
affected the system.
===== Atheros SDIO stack =====
---- host => -------- => neo ---------
*1000B/s ctx_sw CPU *1000B/s ctx_sw CPU
1: 716.06 456 0% 712.71 11990 23%
2: 720.67 391 0% 715.45 12064 25%
3: 723.16 408 0% 717.59 11977 22%
4: 720.36 436 0% 717.59 12021 24%
5: 723.47 433 0% 719.74 12056 25%
6: 715.45 286 0% 709.70 12079 25%
7: 719.74 378 0% 716.06 12035 25%
8: 727.23 489 0% 721.29 12040 24%
9: 718.51 397 0% 713.92 12033 25%
10: 721.60 476 0% 717.59 12086 25%
AVG: 720.62 415 0% 716.16 12038 24%
SDV: 3.35 55 0% 3.23 33 1%
---- neo => --------- => host --------
*1000B/s ctx_sw CPU *1000B/s ctx_sw CPU
1: 809.32 289 5% 802.35 11584 0%
2: 804.28 302 5% 798.92 11600 0%
3: 802.35 292 5% 794.75 11559 0%
4: 798.15 292 5% 792.13 11574 0%
5: 759.15 293 5% 751.67 11621 0%
6: 775.65 291 5% 768.89 11610 0%
7: 793.62 295 5% 785.45 11596 0%
8: 794.38 293 5% 788.40 11548 0%
9: 794.38 295 5% 788.77 11608 0%
10: 791.75 314 5% 784.35 11601 0%
AVG: 792.30 295 5% 785.57 11590 0%
SDV: 13.98 6 0% 14.26 22 0%
host => neo: min /avg /max stddev (100 samples)
15.20/ 72.09/ 293.00 44.88 ms
neo => host: min /avg /max stddev (99 samples)
16.06/ 79.42/ 316.45 50.36 ms
===== Linux SDIO stack =====
---- host => -------- => neo ---------
*1000B/s ctx_sw CPU *1000B/s ctx_sw CPU
1: 709.40 271 0% 704.93 5144 16%
2: 704.04 457 0% 701.98 5664 16%
3: 725.03 364 0% 719.74 5196 16%
4: 734.23 371 0% 728.81 4844 15%
5: 701.10 454 0% 699.63 5889 16%
6: 726.60 416 0% 723.47 4892 16%
7: 730.40 278 0% 726.60 5124 15%
8: 737.78 368 0% 733.91 4748 15%
9: 719.13 428 0% 715.14 5020 15%
10: 731.35 425 0% 727.86 5020 15%
AVG: 721.91 383 0% 718.21 5154 15%
SDV: 12.30 63 0% 11.61 341 0%
---- neo => --------- => host --------
*1000B/s ctx_sw CPU *1000B/s ctx_sw CPU
1: 738.76 937 6% 733.91 11639 0%
2: 734.23 674 5% 728.49 11614 0%
3: 735.84 978 6% 731.35 11629 0%
4: 720.67 701 5% 716.98 11622 0%
5: 724.09 1004 6% 718.82 11615 0%
6: 714.23 945 5% 713.62 11653 0%
7: 711.80 702 5% 707.00 11641 0%
8: 718.20 859 5% 714.23 11626 0%
9: 718.51 762 5% 712.41 11572 0%
10: 741.70 747 6% 736.17 11610 0%
AVG: 725.80 830 5% 721.30 11622 0%
SDV: 10.31 121 0% 9.75 21 0%
host => neo: min /avg /max stddev (100 samples)
16.70/ 81.97/ 427.00 58.35 ms
neo => host: min /avg /max stddev (100 samples)
16.04/ 79.31/ 237.36 42.78 ms
===== Conclusion =====
The throughput results haven't changed. Ping latency is quite similar
with both stacks (and way too large), which makes me wonder if they
may have a common cause.
By the way, the scripts for measurement and report generation are in
http://svn.openmoko.org/developers/werner/wlan-perf/
- Werner
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