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Message-ID: <9f5c7cffc9154d1892cbbc0040d89581@BLUPR03MB373.namprd03.prod.outlook.com>
Date: Fri, 20 Dec 2013 03:35:57 +0000
From: "fugang.duan@...escale.com" <fugang.duan@...escale.com>
To: Hector Palacios <hector.palacios@...i.com>,
Marek Vasut <marex@...x.de>,
"netdev@...r.kernel.org" <netdev@...r.kernel.org>
CC: "Fabio.Estevam@...escale.com" <Fabio.Estevam@...escale.com>,
"shawn.guo@...aro.org" <shawn.guo@...aro.org>,
"l.stach@...gutronix.de" <l.stach@...gutronix.de>,
"Frank.Li@...escale.com" <Frank.Li@...escale.com>,
"bhutchings@...arflare.com" <bhutchings@...arflare.com>,
"davem@...emloft.net" <davem@...emloft.net>
Subject: RE: FEC performance degradation with certain packet sizes
From: Hector Palacios <hector.palacios@...i.com>
Data: Thursday, December 19, 2013 12:44 AM
>To: Marek Vasut; netdev@...r.kernel.org
>Cc: Estevam Fabio-R49496; shawn.guo@...aro.org; l.stach@...gutronix.de; Li
>Frank-B20596; Duan Fugang-B38611; bhutchings@...arflare.com;
>davem@...emloft.net
>Subject: Re: FEC performance degradation with certain packet sizes
>
>Hello,
>
>I'm resending this thread (reworded the subject) with additional people on CC.
>I found the issue happens also with auto-negotiated link and is reproducible on
>the
>i.MX6 as well as on the i.MX28. It looks like a problem with the fec driver.
>
>Steps to reproduce:
>On the target:
> netpipe
>On the host:
> netpipe -h <target_ip> -n 5
>
>At certain packet sizes (starting always at 1533 bytes), the performance drops
>dramatically:
>
>On i.MX28:
>[...]
> 42: 771 bytes 5 times --> 19.78 Mbps in 297.41 usec
> 43: 1021 bytes 5 times --> 23.29 Mbps in 334.41 usec
> 44: 1024 bytes 5 times --> 23.61 Mbps in 330.90 usec
> 45: 1027 bytes 5 times --> 23.43 Mbps in 334.41 usec
> 46: 1533 bytes 5 times --> 0.13 Mbps in 88817.49 usec
> 47: 1536 bytes 5 times --> 0.06 Mbps in 189914.91 usec
> 48: 1539 bytes 5 times --> 0.06 Mbps in 204917.19 usec
> 49: 2045 bytes 5 times --> 0.07 Mbps in 210931.79 usec
> 50: 2048 bytes 5 times --> 0.07 Mbps in 210919.10 usec
> 51: 2051 bytes 5 times --> 0.07 Mbps in 212915.71 usec
> 52: 3069 bytes 5 times --> 35.42 Mbps in 661.01 usec
> 53: 3072 bytes 5 times --> 35.57 Mbps in 659.00 usec
> 54: 3075 bytes 5 times --> 35.42 Mbps in 662.29 usec
> 55: 4093 bytes 5 times --> 40.03 Mbps in 780.19 usec
> 56: 4096 bytes 5 times --> 40.75 Mbps in 766.79 usec
> 57: 4099 bytes 5 times --> 40.64 Mbps in 769.49 usec
> 58: 6141 bytes 5 times --> 3.08 Mbps in 15187.90 usec
> 59: 6144 bytes 5 times --> 2.94 Mbps in 15928.19 usec
> 60: 6147 bytes 5 times --> 5.57 Mbps in 8418.91 usec
> 61: 8189 bytes 5 times --> 1.34 Mbps in 46574.90 usec
> 62: 8192 bytes 5 times --> 2.17 Mbps in 28781.99 usec
> 63: 8195 bytes 5 times --> 1.36 Mbps in 45923.69 usec
> 64: 12285 bytes 5 times --> 51.78 Mbps in 1810.21 usec
> 65: 12288 bytes 5 times --> 50.46 Mbps in 1857.81 usec
> 66: 12291 bytes 5 times --> 54.01 Mbps in 1736.21 usec
> 67: 16381 bytes 5 times --> 55.86 Mbps in 2237.50 usec
> 68: 16384 bytes 5 times --> 56.93 Mbps in 2195.79 usec
> 69: 16387 bytes 5 times --> 35.62 Mbps in 3509.60 usec
> 70: 24573 bytes 5 times --> 7.19 Mbps in 26075.60 usec
> 71: 24576 bytes 5 times --> 58.36 Mbps in 3212.59 usec
> 72: 24579 bytes 5 times --> 7.92 Mbps in 23678.90 usec
> 73: 32765 bytes 5 times --> 58.14 Mbps in 4299.79 usec
> 74: 32768 bytes 5 times --> 5.34 Mbps in 46810.20 usec
> 75: 32771 bytes 5 times --> 41.51 Mbps in 6023.21 usec
> 76: 49149 bytes 5 times --> 49.62 Mbps in 7557.20 usec
> 77: 49152 bytes 5 times --> 48.82 Mbps in 7681.11 usec
>
>On i.MX6:
>[...]
> 42: 771 bytes 5 times --> 16.21 Mbps in 362.91 usec
> 43: 1021 bytes 5 times --> 17.97 Mbps in 433.51 usec
> 44: 1024 bytes 5 times --> 18.19 Mbps in 429.40 usec
> 45: 1027 bytes 5 times --> 18.16 Mbps in 431.41 usec
> 46: 1533 bytes 5 times --> 2.35 Mbps in 4970.11 usec
> 47: 1536 bytes 5 times --> 2.36 Mbps in 4959.91 usec
> 48: 1539 bytes 5 times --> 2.37 Mbps in 4959.20 usec
> 49: 2045 bytes 5 times --> 3.14 Mbps in 4972.31 usec
> 50: 2048 bytes 5 times --> 3.15 Mbps in 4959.50 usec
> 51: 2051 bytes 5 times --> 3.15 Mbps in 4960.01 usec
> 52: 3069 bytes 5 times --> 4.70 Mbps in 4984.19 usec
> 53: 3072 bytes 5 times --> 4.73 Mbps in 4960.10 usec
> 54: 3075 bytes 5 times --> 4.73 Mbps in 4957.81 usec
> 55: 4093 bytes 5 times --> 6.29 Mbps in 4966.71 usec
> 56: 4096 bytes 5 times --> 6.30 Mbps in 4962.00 usec
> 57: 4099 bytes 5 times --> 6.31 Mbps in 4957.71 usec
> 58: 6141 bytes 5 times --> 49.25 Mbps in 951.40 usec
> 59: 6144 bytes 5 times --> 49.23 Mbps in 952.21 usec
> 60: 6147 bytes 5 times --> 49.18 Mbps in 953.69 usec
>
>Does anyone have any clue about where the problem might be?
>
>Best regards,
>--
>Hector Palacios
>
I can reproduce the issue on imx6q/dl platform with freescale internal kernel tree.
This issue must be related to cpufreq, when set scaling_governor to performance:
echo performance > /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
And then do NPtcp test, the result as below:
24: 99 bytes 5 times --> 9.89 Mbps in 76.40 usec
25: 125 bytes 5 times --> 12.10 Mbps in 78.80 usec
26: 128 bytes 5 times --> 12.27 Mbps in 79.60 usec
27: 131 bytes 5 times --> 12.80 Mbps in 78.10 usec
28: 189 bytes 5 times --> 18.00 Mbps in 80.10 usec
29: 192 bytes 5 times --> 18.31 Mbps in 80.00 usec
30: 195 bytes 5 times --> 18.41 Mbps in 80.80 usec
31: 253 bytes 5 times --> 23.34 Mbps in 82.70 usec
32: 256 bytes 5 times --> 23.91 Mbps in 81.70 usec
33: 259 bytes 5 times --> 24.19 Mbps in 81.70 usec
34: 381 bytes 5 times --> 33.18 Mbps in 87.60 usec
35: 384 bytes 5 times --> 33.87 Mbps in 86.50 usec
36: 387 bytes 5 times --> 34.41 Mbps in 85.80 usec
37: 509 bytes 5 times --> 42.72 Mbps in 90.90 usec
38: 512 bytes 5 times --> 42.60 Mbps in 91.70 usec
39: 515 bytes 5 times --> 42.80 Mbps in 91.80 usec
40: 765 bytes 5 times --> 56.45 Mbps in 103.40 usec
41: 768 bytes 5 times --> 57.11 Mbps in 102.60 usec
42: 771 bytes 5 times --> 57.22 Mbps in 102.80 usec
43: 1021 bytes 5 times --> 70.69 Mbps in 110.20 usec
44: 1024 bytes 5 times --> 70.70 Mbps in 110.50 usec
45: 1027 bytes 5 times --> 69.59 Mbps in 112.60 usec
46: 1533 bytes 5 times --> 73.56 Mbps in 159.00 usec
47: 1536 bytes 5 times --> 72.92 Mbps in 160.70 usec
48: 1539 bytes 5 times --> 73.80 Mbps in 159.10 usec
49: 2045 bytes 5 times --> 93.59 Mbps in 166.70 usec
50: 2048 bytes 5 times --> 94.07 Mbps in 166.10 usec
51: 2051 bytes 5 times --> 92.92 Mbps in 168.40 usec
52: 3069 bytes 5 times --> 123.43 Mbps in 189.70 usec
53: 3072 bytes 5 times --> 123.68 Mbps in 189.50 usec
Thanks,
Andy
--
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