Application Report
SPRA642 - March 2000
1
TMS320C62x
, TMS320C67x
DSP Cache Performance
on Vocoder Benchmarks
Philip Baltz C6000
DSP Applications
ABSTRACT
This application report discusses several multichannel vocoder benchmarks run on the
TMS320C6000 DSP platform devices including:
•TMS320C6201 (C6201)
•TMS320C6202 (C6202)
•TMS320C6203 (C6203)
•TMS320C6204 (C6204)
•TMS320C6205 (C6205)
•TMS320C6211 (C6211)
•TMS320C6701 (C6701)
•TMS320C6711 (C6711)
The C6201, C6202, C6203, C6204, C6205, and C6701 have a Harvard internal memory
architecture with an on-chip program cache. The C6211 and C6711 have a two-level cache
architecture with dedicated level-one data (L1D) and level-one program (L1P) caches and
a unified level-two (L2) cache. The benchmarks include the following vocoders:
•G.729
•G.729a
•G.723
•GSM
•EVRC
•Combinations of the above
The results show that the C621 1 performs at 82 – 92%, and the C6201 performs at 87 – 98%
cycle efficiency of optimal performance, even when multiple channels or multiple vocoders
are all running concurrently. With its large computational power and small device size, the
C6203 achieves a very high channel density on these vocoders. The C6204 and C621 1 offer
good performance on these vocoders at a very low cost per channel.
These ITU vocoder algorithms are compiled from their respective C code. They have
varying degrees of optimization at the C and/or assembly level, but are not fully
optimized. Better implementations may be available from third party vendors. They are
used here to illustrate the efficiency of the internal memory architectures of C6000
devices.
TMS320C62x, TMS320C67x, C6000, and TMS320C6000 are trademarks of Texas Instruments Incorporated.
SPRA642
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TMS320C62x
, TMS320C67x
DSP Cache Performance on Vocoder Benchmarks
Contents
1 Device Descriptions and Performance Measurements 3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2 Vocoder Descriptions 5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3 Benchmark Descriptions 5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4 Benchmark Memory Usage 6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5 Execution Times by Benchmark Sets 7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.1 Single Vocoder, Single Channel Execution Time 7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.2 Single Vocoder, Multiple Channels Execution Time 8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.3 Multiple Vocoders, Single Channel Execution Time 12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.4 Multiple Vocoders, Multiple Channels Execution Time 13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Appendix A Pricing Information 17. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
List of Figures
Figure 1. Single Vocoder, Single Channel Execution Time by Device 8. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 2. Measured Maximum Vocoder Channels by Device 9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 3. Channel Loading by Device 10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 4. Normalized Cost ($) per Channel of Vocoders by Device 11. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 5. Multiple Vocoders, Single Channel Execution Time by Device 13. . . . . . . . . . . . . . . . . . . . . . . . .
Figure 6. Measured Maximum Vocoder Channels by Device 14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 7. Channel Loading by Device 15. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 8. Normalized Cost ($) per Channel of Vocoders by Device 15. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 9. C6211 and C6201 Efficiency vs. Code Size 16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
List of Tables
Table 1. TMS320C62x/TMS320C67x Device Comparison 4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Table 2. Benchmark Memory Usage by Device 7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Table 3. Single Vocoder, Single Channel Execution Cycles by Device 7. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Table 4. Single Vocoder, Single Channel Execution Time (ms) by Device 8. . . . . . . . . . . . . . . . . . . . . . . . .
Table 5. Measured Maximum Vocoder Channels by Device 9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Table 6. Device Loading at Maximum Vocoder Channels 9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Table 7. Channel Loading (MHz/Channel) by Device 10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Table 8. Normalized Cost ($) per Channel of Vocoders by Device 10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Table 9. Normalized Efficiency by Device 11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Table 10. Instruction Size Maximum Vocoder Channels 12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Table 11. Multiple Vocoders, Single Channel Execution Cycles by Device 12. . . . . . . . . . . . . . . . . . . . . . .
Table 12. Multiple Vocoders, Single Channel Execution Time (ms) by Device 12. . . . . . . . . . . . . . . . . . . .
Table 13. Measured Maximum Vocoder Channels by Device 13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Table 14. Device Loading at Maximum Vocoder Channels 14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Table 15. Channel Loading (MHz/Channel) by Device 14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Table 16. Normalized Cost ($) per Channel of Vocoders by Device 15. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Table 17. Normalized Efficiency by Device 16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Table 18. Instruction Size (Kbytes) of Maximum Vocoder Channels by Device 16. . . . . . . . . . . . . . . . . . .
Table A–1. Cost Calculations 17. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SPRA642
3
TMS320C62x
, TMS320C67x
DSP Cache Performance on Vocoder Benchmarks
1 Device Descriptions and Performance Measurements
The TMS320C6000 DSPs use one of two internal memory architectures:
•Harvard
•Two-level Cache
Table 1 describes the internal memory architecture as well as other features of these devices.
The TMS320C620x/TMS320C6701 devices employ a Harvard architecture internally, with
dedicated program and data memories. The C6202 and C6203 share an identical internal
memory architecture. These devices differ in the type of host port employed and in their core
operating voltage. The C6701 shares a very similar architecture to the C6201/C6204/C6205 with
the exception that the internal data memory is widened to allow loading of two 64-bit values
every cycle. In comparison to the C6201, the C6202 and C6203 increase on-chip memory for
both program and data. Cycle results for the C6201 were measured on the C6201 Multichannel
Evaluation Module (MCEVM).
The C6202 and C6203 were measured on internal validation boards for these devices. The
C6204 and C6205 cycle results are assumed to be identical to those of the C6201. Performance
metrics on C6204 and C6205 refer to the C6201 data point in the graphs. C6701 cycle counts
can be assumed to be the same as for the those of the C6201/C6204/C6205. However, the total
performance is 83%, since the frequency of the C6701 is 167 MHz vs. 200 MHz for the others.
This difference in frequency can be directly related to execution time but not to channel
performance. For this reason, note that the C6701 has been included in the tables that show
execution time performance, but
not
in tables that present channel performance.
The C6211 and C6711 processors employ a two-level cache to achieve near optimal
performance on a low-cost device with only a limited amount of internal memory. Results for the
C6211 were determined on a C6211 DSP Starter Kit (DSK). Results on a C6711 can be
assumed to be identical to C6211, and you should refer to the C6211 data point in all graphs.
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TMS320C62x
, TMS320C67x
DSP Cache Performance on Vocoder Benchmarks
Table 1. TMS320C62x/TMS320C67x Device Comparison
Device C6211
C6711
C6201,
C6204/C6205,
C6701 C6202 C6203
Frequency 150 MHz 200 MHz (C6201)
200 MHz (C6204/C6205)
167 MHz (C6701)
250 MHz 300 MHz
Internal Memory
Architecture Two-level cache Harvard with program cache
Total Internal
Memory (Bytes) 72K 128K 384K 796K
Dedicated Program
(Bytes) 4K 64K 256K 384K
Internal Program
Architecture Cache 1 block:
64K-mapped /cache 2 blocks:
64K-mapped/cache
64K-mapped
2 blocks:
64K-mapped/cache
128K-mapped
Dedicated Data Bytes 4K 64K 128K 512K
Internal Data
Architecture Cache Mapped
Internal Unified
Memory 64K Does not apply
DMA Controller 16-channel
Enhanced 4 channels
Serial Port (McBSPs) 2 3
32-bit Timers 2
Host Port 16-bit HPI 16-bit HPI (C6201)
16-bit HPI (C6701)
32-bit XBUS (C6204)
PCI (C6205) 32-bit XBUS
IO Voltage 3.3V
Core Voltage 1.8V 1.8V (C6201/C6701)
1.5V (C6204/C6205) 1.8 V
1.5V planned 1.5V
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TMS320C62x
, TMS320C67x
DSP Cache Performance on Vocoder Benchmarks
2 Vocoder Descriptions
The benchmark vocoders are Code Excited Linear Prediction (CELP) vocoders which process
speech signals by dividing the speech signal into segments (or frames) and operating on one
frame at a time.
•GSM: This is the enhanced full rate (EFR) GSM vocoder. The frame is 20-ms long (or 160
samples with 8kbits/sec sampling rate). The Linear Prediction Coefficients (LPC) parameters
are extracted twice per frame. Each frame is equally divided further into four subframes.
Pitch value and gain, and stochastic codebook and gain are obtained once per subframe
(with the analysis-by-synthesis method). Encoding rate is 13 kbps.
•EVRC: This is the vocoder used in IS-95 cellular standard. The frame is 20-ms long. It is a
variable rate vocoder with three operational rates: full, half and 1/8, depending on the
contents of the current frame. For the full and half rates, LPC and pitch value and gain are
obtained once per frame. Then each frame is divided into three subframes with 53, 53, and
54 speech samples. The stochastic codebook and its gain are searched once per subframe.
For the 1/8 rate, only the LPC parameters and the frame energy are extracted. Encoding
rate is variable.
•G.729: This vocoder divides speech into 10-ms frames. Each frame is divided further into
two subframes. LPC is updated once per frame, and the rest of the parameters are updated
once per subframe. Encoding rate is 8 kbps.
•G.729A: This vocoder is the same as G.729, except a simplified version of the stochastic
codebook search method. Encoding rate is 8 kbps.
•G.723: This vocoder divides speech into 30-ms frames. Each frame is divided further into
four subframes. LPC is updated once per frame, and the rest of the parameters are updated
once per subframe. The G.723 vocoder can work under two encoding rates: ~5.5 kbps and
~6.5 kbps.
3 Benchmark Descriptions
Four benchmark sets were tested on each device. These benchmark sets are:
•Single Vocoder, Single Channel
•Single Vocoder, Multiple Channels
•Multiple Vocoders, Single Channel
•Multiple Vocoders, Multiple Channels
Sixteen different benchmarks were run on each processor.
1. Single Vocoder, Single Channel: A single channel of each vocoder (GSM, EVRC,
G.729, G.729a, and G.723) was run on each device. (5 Benchmarks)
2. Single Vocoder, Multiple Channels: The maximum number of channels of each vocoder
(GSM, EVRC, G.729, G.729a, and G.723) were run on each device. (5 Benchmarks)
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TMS320C62x
, TMS320C67x
DSP Cache Performance on Vocoder Benchmarks
3. Multiple Vocoders, Single Channel (3 Benchmarks):
– Multichannel FrameWork (MCFW) MCFW uses each of the vocoders (GSM, EVRC,
G.729, G.729a, and G.723).
– Multichannel Voice over Internet Protocol (MCVoIP) MCVoIP uses the G.729,
G7.29A, and G.723 vocoders.
– Multichannel wireless (MCwireless) MCwireless uses the GSM and EVRC vocoders.
4. Multiple Vocoders, Multiple Channels (3 Benchmarks): This was done for each of the
multiple vocoder sets (MCFW, MCVoIP, MCwireless).
Identical vocoder source code was used on each processor. There were no optimizations or
considerations made for cache or peripheral architecture, except to use the DMA to move data
on and off chip when appropriate. For this reason, the performance numbers presented might be
improved with additional optimizations.
4 Benchmark Memory Usage
Because processors have memory sizes that vary, each benchmark on each processor uses its
own set of memory configurations. Table 2 details the usage of internal memory for each
benchmark by processor type.
•Because of the small on-chip memory on the low-cost C6211 and C6711, both program and
data are loaded in external memory, and the L2 is enabled as a 64K-byte cache.
•Because all vocoder programs are larger than 64K bytes (C6201, C6204, C6205, C6701),
the program is loaded in external memory, and the program cache is enabled. On the single
channel, single vocoder benchmarks; data is loaded on chip. In every other case, these
data cannot fit on chip and are divided between internal and external memory. The DMA
pages context data in and out of external memory on a context switch.
•The C6202 has 4x the program memory of C6201 and can typically store up to three
vocoders. Thus, for all benchmarks except MCFW, all program is loaded in internal memory.
For MCFW, program is loaded in external memory and the instruction cache is enabled. For
single channel, single vocoder benchmarks; data is loaded in internal memory. For all other
benchmarks, the data is divided between internal and external memory, and the DMA moves
data on and off chip as necessary.
•On the C6203, across all benchmarks in this application note, because of the its large
on-chip memories, all program and data are loaded in internal memory and the instruction
cache is disabled.
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TMS320C62x
, TMS320C67x
DSP Cache Performance on Vocoder Benchmarks
Table 2. Benchmark Memory Usage by Device
Benchmark Sets Vocoder
Description Memory C6211, C6711 C6201, C6204,
C6205, C6701 C6202 C6203
Single Vocoder,
GSM
Program Cache Cache Internal Internal
Single
Vocoder
,
Single Channel
GSM
EVRC
G 729
Data Cache Internal Internal Internal
Single Vocoder, G.729
G.729A Program Cache Cache Internal Internal
Single
Vocoder,
Multiple Channel
G.729A
G.723 Data Cache DMA DMA Internal
MCwireless Program Cache Cache Internal Internal
Multi
p
le Vocoders
,
MCwireless
MCVoIP Data Cache DMA DMA Internal
M
u
ltiple
Vocoders
,
Single Channel Each
MCFW
Program Cache Cache Cache Internal
MCFW Data Cache DMA DMA Internal
MCwireless Program Cache Cache Internal Internal
Multiple Vocoder,
M ltiple Channels
MCwireless
MCVoIP Data Cache DMA DMA Internal
Multiple Channels
Each
MCFW
Program Cache Cache Cache Internal
Each
MCFW Data Cache DMA DMA Internal
5 Execution Times by Benchmark Sets
5.1 Single Vocoder, Single Channel Execution Time
The first benchmark set measures the execution time of a single channel of each individual
vocoder for each device. Table 3 lists the number of cycles required to execute 120-ms† data for
each vocoder by device. Table 4 lists the execution time for each vocoder.
Table 3. Single Vocoder, Single Channel Execution Cycles by Device
Vocoder C6211, C6711 C6201, C6204,
C6205, C6701 C6202 C6203
GSM 1,750,696 1,507,596 1,474,472 1,474,912
G.729a 1,971,212 1,922,752 1,801,772 1,801,772
G.729 4,781,700 4,630,584 4,372,448 4,372,448
G.723 1,639,492 1,456,768 1,400,976 1,400,956
EVRC 3,067,876 2,807,328 2,656,768 2,656,824
†120 ms was chosen since 120 ms is a multiple of the frame size for each of the vocoders. GSM and EVRC use a 20-ms frame size,
G.729 and G.729a use a 10-ms frame size, and G.723 uses a 30-ms frame size.
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TMS320C62x
, TMS320C67x
DSP Cache Performance on Vocoder Benchmarks
Table 4. Single Vocoder, Single Channel Execution Time (ms) by Device
Vocoder C6211, C6711
(150 MHz)
C6201,
C6204, C6205†
(200 MHz) C6202
(250 MHz) C6203
(300 MHz)
GSM 11.7 7.5 5.9 4.9
G.729a 13.1 9.6 7.2 6.0
G.729 31.9 23.2 17.5 14.6
G.723 10.9 7.3 5.6 4.7
EVRC 20.5 14.0 10.6 8.9
†C6701 execution time would scale these results by 5/6.
Figure 1 illustrates execution time decreasing as the speed of the processor increases, as
expected. Since the change in the execution time between the C6211 and C6201 is greater than
the change between the C6201 and the C6202, or C6202 and C6203; note that there is some
performance loss on C6211 because of its smaller memory. However, as shown later in this
application report, the small performance loss is much less significant than the cost difference of
the C6211 and the C6201 (see Appendix A for pricing information).
0
5
10
15
20
25
30
35
C6211 C6201 C6202 C6203
Device
Execution Time (ms)
GSM
729a
729
723
EVRC
(150 MHz) (200 MHz) (250 MHz) (300 MHz)
Figure 1. Single Vocoder, Single Channel Execution Time by Device
The next section shows that performance loss is limited, and the device family provides an
attractive set of performance versus cost/performance tradeoffs for the system designer.
5.2 Single Vocoder, Multiple Channels Execution Time
The second benchmark set measures the maximum number of channels of each individual
vocoder that can be run on each device. The number of channels is determined by measuring
how many channels can be executed in 120 ms (see footnote on page 7). Table 5 lists the
number of channels that can execute on each device. The cycle-count measurements are then
taken from a multichannel implementation actually running on the device. Thus, all the effects of
switching contexts between channels is taken into account. Figure 2 shows that the number of
channels executed increases as the speed of the processor increases.
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TMS320C62x
, TMS320C67x
DSP Cache Performance on Vocoder Benchmarks
Table 5. Measured Maximum Vocoder Channels by Device
Vocoder C6211, C6711
(150 MHz)
C6201,
C6204, C6205
(200 MHz) C6202
(250 MHz) C6203
(300 MHz)
GSM 10 15 19 24
G.729a 8 121519
G.729 3568
G.723 11 16 21 25
EVRC 5 8 11 13
0
5
10
15
20
25
30
C6211 C6201 C6202 C6203
Device
Maximum Channels
GSM
729a
729
723
EVRC
(150 MHz) (200 MHz) (250 MHz) (300 MHz)
Figure 2. Measured Maximum Vocoder Channels by Device
Table 6 lists the loading for each device, by vocoder, when executing the maximum number of
vocoder channels. These values are calculated by dividing the total execution time for the
maximum number of channels by 120 ms (see footnote on page 7). A larger device-loading
percentage is not necessarily better. For instance, if the device must execute another task in
addition to executing a vocoder, then 100% loading by the vocoder means that the number of
vocoder channels needs to be reduced to make execution room for the other task. If the device
only executes the vocoder, then 100% utilization is optimal.
Table 6. Device Loading at Maximum Vocoder Channels
Vocoder C6211, C6711
(%)
C6201,
C6204, C6205
(%) C6202
(%) C6203
(%)
GSM 99 94 96 98
G.729a 94 100 95 98
G.729 80 100 88 98
G.723 98 98 99 97
EVRC 84 94 98 96
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TMS320C62x
, TMS320C67x
DSP Cache Performance on Vocoder Benchmarks
Table 7 and Figure 3 show the channel loading for each vocoder by device. Channel loading is
calculated by dividing the device speed by the number of channels executed on the device. This
results in the amount of device resources required to execute a single channel. This number is
then scaled by the device loading shown in Table 6, so that a comparison can be made
according to the amount of resources that are actually used to execute the vocoder.
Table 7. Channel Loading (MHz/Channel) by Device
Vocoder C6211, C6711 C6201,
C6204, C6205 C6202 C6203
GSM 14.9 12.5 12.6 12.3
G.729a 17.7 16.7 15.9 15.4
G.729 40.0 40.0 36.8 36.6
G.723 13.4 12.3 11.8 11.6
EVRC 25.3 23.6 22.3 22.1
0
5
10
15
20
25
30
35
40
45
C6211 C6201 C6202 C6203
Device
Channel Loading
(MHz/Channel)
GSM
729a
729
723
EVRC
(150 MHz) (200 MHz) (250 MHz) (300 MHz)
Figure 3. Channel Loading by Device
Table 8 and Figure 4 show the cost per vocoder channel when the device is executing the
maximum number of vocoder channels possible (see Appendix A for pricing information). The
cost is normalized by device loading to accurately represent the cost of executing the maximum
channels on each device.
Table 8. Normalized Cost ($) per Channel of Vocoders by Device
Vocoder C6204 C6211 C6201 C6202 C6203
GSM $2.93 $3.97 $6.29 $8.16 $7.35
G.729a $3.89 $4.71 $8.35 $10.25 $9.21
G.729 $9.33 $10.67 $20.04 $23.83 $21.88
G.723 $2.86 $3.57 $6.16 $7.65 $6.94
EVRC $5.49 $6.74 $11.80 $14.47 $13.23
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TMS320C62x
, TMS320C67x
DSP Cache Performance on Vocoder Benchmarks
0
5
10
15
20
25
30
C6204 C6211 C6201 C6202 C6203
Device
Cost/Channel ($)
GSM
729a
729
723
EVRC
(150 MHz)(200 MHz) (200 MHz)(250 MHz)(300 MHz)
Figure 4. Normalized Cost ($) per Channel of Vocoders by Device
Table 9 lists the efficiency for each device on the five vocoders. Since all program and data fit on
chip for the C6203, its results are nearest to optimal. Thus, C6203 performance is used as the
baseline for the comparison. The efficiency is calculated by scaling the execution time by
frequency, then normalizing that by device loading. This normalized, scaled execution
performance is then divided by the baseline performance on the C6203 to obtain the efficiency.
The resulting numbers show that the two-level cache on the C6211 is very efficient and runs
between 82% and 91% of a device which does not stall for external memory accesses. The
C6201 performs at 91% to 98% efficiency, thus the C6201 cache is very efficient. The C6202
operates at above 97% efficiency, thus data paging on the C6202 does not significantly affect
performance.
Table 9. Normalized Efficiency by Device
C6211, C6711 C6201, C6204,
C6205, C6701 C6202 C6203
Program Cache Cache On-Chip On-Chip
Data Cache Paged by DMA Paged by DMA On-Chip
GSM 83% 98% 98% 100%
G.729a 87% 92% 97% 100%
G.729 92% 92% 99% 100%
G.723 87% 94% 98% 100%
EVRC 87% 94% 99% 100%
Table 10 lists the size of the program by vocoder when executing the maximum number of
vocoder channels. The program size is similar for each of the devices across all vocoders. This
indicates that any differences in performance are not due to a disparate amount of program
fetch cycles. Since each device operates on the same data on a particular vocoder, the data
sizes are identical and do not cause any differences in device performance.
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TMS320C62x
, TMS320C67x
DSP Cache Performance on Vocoder Benchmarks
Table 10. Instruction Size Maximum Vocoder Channels
Vocoder Instruction
Size (Kbytes)
GSM 75
G.729a 95
G.729 95
G.723 79
EVRC 91
5.3 Multiple Vocoders, Single Channel Execution Time
The third benchmark set measures the execution time of a single channel of one of three
multiple vocoder tests.
For the multiple vocoders, single channel tests; each multiple vocoder test is run with one
channel of each included vocoder. For example, the MCwireless test runs 120 ms (see footnote
on page 7) of data on both the GSM and EVRC vocoders. Table 11 lists the number of cycles
required to execute 120 ms of data on each multiple vocoder test. Table 12 lists the execution
time for each vocoder test. Figure 5 illustrates these results graphically.
Table 11. Multiple Vocoders, Single Channel Execution Cycles by Device
C6211, C6711 C6201, C6204,
C6205, C6701 C6202 C6203
MCFW 13,901,344 13,417,596 12,794,156 11,575,480
MCVoIP 8,755,896 8,481,584 7,580,364 7,551,992
MCwireless 5,051,336 4,626,560 4,106,112 4,076,024
Table 12. Multiple Vocoders, Single Channel Execution Time (ms) by Device
C6211, C6711
(150 MHz)
C6201, C6204,
C6205†
(200 MHz) C6202
(250 MHz) C6203
(300 MHz)
MCFW 92.7 67.1 51.2 38.6
MCVoIP 58.4 42.4 30.3 25.2
MCwireless 33.7 23.1 16.4 13.6
†C6701 execution time can be assumed to be 5/6 of these values as it runs at 167 MHz.
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0
10
20
30
40
50
60
70
80
90
100
C6211 C6201 C6202 C6203
Device
Execution Time (ms)
MCFW
MCVoIP
MCwireless
(150 MHz) (200 MHz) (250 MHz) (300 MHz)
Figure 5. Multiple Vocoders, Single Channel Execution Time by Device
5.4 Multiple Vocoders, Multiple Channels Execution Time
The fourth benchmark set measures the maximum number of channels of each multiple vocoder
test that can be executed on each device. The number of channels is determined by measuring
how many channels can be executed in 120 ms (see footnote on page 7). The number of
channels of each vocoder in each multiple vocoder test is the same. For example, on the C6201,
only one channel of G.729, G.729a, and G.723 is used in the MCFW test even though there is
enough computational power available to execute multiple G.723 channels concurrent with one
G.729 and one G.729a channel. Table 13 lists the maximum number of channels that can
execute on each device. Figure 6 illustrates that the maximum number of channels increases
with operating frequency.
Table 13. Measured Maximum Vocoder Channels by Device
C6211, C6711
(150 MHz)
C6201, C6204,
C6205
(200 MHz) C6202
(250 MHz) C6203
(300 MHz)
MCFW 1123
MCVoIP 2234
MCwireless 3578
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0
1
2
3
4
5
6
7
8
9
C6211 C6201 C6202 C6203
Device
Maximum Channels
MCFW
MCVoIP
MCwireless
(150 MHz) (200 MHz) (250 MHz) (300 MHz)
Figure 6. Measured Maximum Vocoder Channels by Device
Table 14 lists the loading for each device by vocoder when executing the maximum number of
vocoder channels. These values are calculated by dividing the total execution time for the
maximum number of channels by 120 ms (see footnote on page 7).
Table 14. Device Loading at Maximum Vocoder Channels
C6211, C6711
(150 MHz)
C6201, C6204,
C6205
(200 MHz) C6202
(250 MHz) C6203
(300 MHz)
MCFW 78% 56% 83% 98%
MCVoIP 96% 70% 77% 84%
MCwireless 82% 92% 98% 90%
Table 15 lists the channel loading for each vocoder by device. Figure 7 shows this data
graphically. Channel loading is calculated by dividing the device speed by the number of
channels executed on the device, and scaling it by the device-loading percentage shown in
Table 14.
Table 15. Channel Loading (MHz/Channel) by Device
C6211, C6711 C6201, C6204,
C6205, C6701 C6202 C6203
MCFW 116.3 111.6 104.1 97.5
MCVoIP 71.9 70.0 63.9 63.2
MCwireless 40.9 36.7 34.8 34.1
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0
20
40
60
80
100
120
140
C6211 C6201 C6202 C6203
Device
Channel Loading
(MHz/Channel)
MCFW
MCVoIP
MCwireless
(150 MHz) (200 MHz) (250 MHz) (300 MHz)
Figure 7. Channel Loading by Device
Table 16 and Figure 8 show the cost per vocoder channel by device when the device is
executing the maximum number of multiple vocoder channels possible (see Appendix A for
pricing information). This data is normalized by device loading.
Table 16. Normalized Cost ($) per Channel of Vocoders by Device
C6204 C6211 C6201 C6202 C6203
MCFW $26.02 $31.00 $55.92 $67.44 $58.35
MCVoIP $16.32 $19.16 $35.07 $41.40 $37.79
MCwireless $8.55 $10.89 $18.38 $22.55 $20.38
0
10
20
30
40
50
60
70
80
C6204 C6211 C6201 C6202 C6203
Device
Cost/Channel ($)
MCFW
MCVoIP
MCwireless
(200 MHz) (150 MHz)(200 MHz)(250 MHz) (300 MHz)
Figure 8. Normalized Cost ($) per Channel of Vocoders by Device
Table 17 lists the efficiency for each device on each of the multi-vocoder tests. These results are
calculated by normalizing and scaling execution times for each test. The resulting numbers show
that the two-level cache of the C6211 is very efficient and runs between 83% and 88% of a
device which does not stall for external memory accesses. The C6201 performs better, and
achieves between 87% and 93% efficiency.
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Table 17. Normalized Efficiency by Device
C6211, C6711 C6201, C6204,
C6205, C6701 C6202 C6203
Program Cache Cache On-Chip On-Chip
Data Cache Paged by DMA Paged by DMA On-Chip
MCFW 84% 87% 94% 100.0%
MCVoIP 88% 90% 99% 100.0%
MCwireless 83% 93% 98% 100.0%
Table 18 lists the size of the instruction for each device by vocoder when executing the
maximum number of vocoder channels. The program size is similar for each of the devices
across all vocoder tests. Any differences in performance are not due to a disparate amount of
program fetch cycles. Since each device operates on the same data on a particular vocoder test,
the data sizes are identical and do not cause any differences in device performance.
Table 18. Instruction Size (Kbytes) of Maximum Vocoder Channels by Device
Application Instruction
Size (Kbytes)
MCFW 305
MCVoIP 163
MCwireless 154
Figure 9 illustrates the efficiency numbers presented in Table 16 and Table 17 for the C6211 and
C6201. This graph shows that both of these devices attain high levels of cache performance,
even on very large data sizes.
0%
20%
40%
60%
80%
100%
0 150 300 450 600 750
Cached Data Size
Efficiency
C6211
C6201
Figure 9. C6211 and C6201 Efficiency vs. Code Size
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Appendix A Pricing Information
The following pricing, used for comparisons and channel costs in this Application Report, is for
25K unit purchases. These prices are accurate as of December 1, 1999.
Table A–1. Cost Calculations
Device C6211 C6201 C6202 C6203 C6204
Price $25.00 $85.21 $146.92 $179.53 $31.63
SDRAM†$15.00‡$15.00‡$15.00‡$15.00 $15.00
Total $40.00 $100.21 $161.92 $194.53 $46.63
†The SDRAM used for comparison is the 16-Mbit, Micron part number MT48LC1M16A1TG-7 S, with a per-unit cost of $7.50.
‡The cost calculations for the C6211, C6201, and C6202 devices also include the cost of external SDRAM.
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