On Sun, Nov 27, 2011 at 8:18 PM, Woodruff, Richard <r-woodru...@ti.com> wrote:
>
>> From: linaro-dev-boun...@lists.linaro.org [mailto:linaro-dev-
>> boun...@lists.linaro.org] On Behalf Of Mans Rullgard
>
>> >> Do you have an erratum number for this?
>> >>
>> > This was very recent BUG and not yet made it to the public errata
>> > numbers. Most likely next PL310 errata update should have
>> > this one documented.
>>
>> Do you have _any_ identifier for it?
>
> ARM expanded errata 752271 to cover DLF not working till r3p2 in errata
> version 13.1 (21 Nov 11), 4460 is r3p1-50rel0 and is impacted.
Thanks a lot. Your posts are very informative as usual.
By the way, do you know whether it is safe to use "SCU Speculative
linefills" with Cortex-A9 r2pX and PL310 r3pX?
http://infocenter.arm.com/help/topic/com.arm.doc.ddi0407f/BABEBFBH.html
As a quick and dirty test, it can be enabled in
'arch/arm/kernel/smp_scu.c' by just setting extra (1 << 3) bit in SCU
Control Register from 'scu_enable' function. In my tests, this seems
to reduce L2 cache access latency a bit with an overall ~1.5%
performance improvement at least for 7zip data compression. This is
not a huge boost, but still would be nice to have unless some errata
prevent this feature from being enabled.
Synthetic random read latency benchmark (extra overhead caused by L1
cache misses) and also a bit more realistic p7zip benchmark results on
origenboard (Exynos 4210 @1.2GHz) are listed below.
=== SCU Speculative linefills disabled ===
block size : random read access time
1024 : 0.0 ns
2048 : 0.0 ns
4096 : 0.0 ns
8192 : 0.0 ns
16384 : 0.0 ns
32768 : 0.1 ns
65536 : 9.1 ns
131072 : 13.8 ns
262144 : 19.0 ns
524288 : 21.6 ns
1048576 : 31.0 ns
2097152 : 86.2 ns
4194304 : 117.2 ns
8388608 : 134.5 ns
16777216 : 146.4 ns
33554432 : 155.9 ns
67108864 : 164.7 ns
# ./7za b -mmt=1
7-Zip (A) 9.20 Copyright (c) 1999-2010 Igor Pavlov 2010-11-18
p7zip Version 9.20 (locale=C,Utf16=off,HugeFiles=on,2 CPUs)
RAM size: 477 MB, # CPU hardware threads: 2
RAM usage: 419 MB, # Benchmark threads: 1
Dict Compressing | Decompressing
Speed Usage R/U Rating | Speed Usage R/U Rating
KB/s % MIPS MIPS | KB/s % MIPS MIPS
22: 752 100 730 732 | 12665 100 1146 1143
23: 736 100 750 750 | 12469 100 1141 1141
24: 717 100 770 771 | 12289 100 1139 1140
25: 694 100 793 792 | 12103 100 1138 1138
----------------------------------------------------------------
Avr: 100 761 761 100 1141 1141
Tot: 100 951 951
7-Zip (A) 9.20 Copyright (c) 1999-2010 Igor Pavlov 2010-11-18
p7zip Version 9.20 (locale=C,Utf16=off,HugeFiles=on,2 CPUs)
RAM size: 477 MB, # CPU hardware threads: 2
RAM usage: 419 MB, # Benchmark threads: 1
Dict Compressing | Decompressing
Speed Usage R/U Rating | Speed Usage R/U Rating
KB/s % MIPS MIPS | KB/s % MIPS MIPS
22: 751 100 730 730 | 12675 100 1144 1144
23: 736 100 750 750 | 12483 100 1143 1143
24: 716 100 770 770 | 12300 100 1142 1141
25: 693 100 792 792 | 12113 100 1139 1139
----------------------------------------------------------------
Avr: 100 760 760 100 1142 1142
Tot: 100 951 951
=== SCU Speculative linefills enabled ===
block size : random read access time
1024 : 0.0 ns
2048 : 0.0 ns
4096 : 0.0 ns
8192 : 0.0 ns
16384 : 0.0 ns
32768 : 0.1 ns
65536 : 7.5 ns
131072 : 11.1 ns
262144 : 16.3 ns
524288 : 19.0 ns
1048576 : 33.2 ns
2097152 : 82.9 ns
4194304 : 113.1 ns
8388608 : 130.5 ns
16777216 : 143.2 ns
33554432 : 151.6 ns
67108864 : 160.3 ns
# ./7za b -mmt=1
7-Zip (A) 9.20 Copyright (c) 1999-2010 Igor Pavlov 2010-11-18
p7zip Version 9.20 (locale=C,Utf16=off,HugeFiles=on,2 CPUs)
RAM size: 479 MB, # CPU hardware threads: 2
RAM usage: 419 MB, # Benchmark threads: 1
Dict Compressing | Decompressing
Speed Usage R/U Rating | Speed Usage R/U Rating
KB/s % MIPS MIPS | KB/s % MIPS MIPS
22: 764 100 742 743 | 12721 100 1150 1148
23: 746 100 761 760 | 12535 100 1147 1147
24: 726 100 781 781 | 12362 100 1145 1147
25: 704 100 804 804 | 12170 100 1145 1144
----------------------------------------------------------------
Avr: 100 772 772 100 1147 1147
Tot: 100 959 959
7-Zip (A) 9.20 Copyright (c) 1999-2010 Igor Pavlov 2010-11-18
p7zip Version 9.20 (locale=C,Utf16=off,HugeFiles=on,2 CPUs)
RAM size: 479 MB, # CPU hardware threads: 2
RAM usage: 419 MB, # Benchmark threads: 1
Dict Compressing | Decompressing
Speed Usage R/U Rating | Speed Usage R/U Rating
KB/s % MIPS MIPS | KB/s % MIPS MIPS
22: 764 100 745 744 | 12732 100 1148 1149
23: 747 100 761 762 | 12542 100 1149 1148
24: 728 100 783 783 | 12366 100 1147 1147
25: 706 100 806 806 | 12179 100 1145 1145
----------------------------------------------------------------
Avr: 100 774 773 100 1147 1147
Tot: 100 960 960
--
Best regards,
Siarhei Siamashka
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