PC Specification
QT
RACE
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U
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ANUAL
© 2018 PDQLogic Ltd.
QTrace User Manual Rev 1.01
Page 46
10.
PC Specification
The specification of the PC on which the QTrace Analyser is running will have a significant impact on the
target speed that can be reliably traced. The QTrace Analyser application continuously decompresses
and decodes data streamed by the QTrace probe into machine instructions executed by the target. It
must do this quickly enough to avoid missing incoming data and with minimal latency to give a
responsive UI. Most modern PC will be capable of running the QTrace Analyser with no problem.
A comparison of QTrace Analyser performance running on different PCs is shown in Table 10 below. The
same target application was run on a STM32F446 processor running at 168MHz. The target execution
rate is approximately 97 MIPS and the incoming USB data rate is 17MB/s. The combination of the target
instruction rate and the incoming data rate dictates the level of processing required by the QTrace
Analyser.
The key indicator of how the QTrace Analyser is performing is the average decode rate. It shows how
much faster the trace data is being processed compared with the incoming data rate. The decode rate
will periodically drop as other applications require CPU processing and when Windows runs its core
services. A sustained drop in available CPU processing power that causes the decode rate to drop below
the incoming data rate will result in a buffer overflow and trace data loss. Therefore the faster the
decode rate, the more margin there to avoid data overflow.
System
CPU
Physical
Cores
RAM
QTrace Analyser
CPU Usage
Average
Decode Rate
Dell XPS 15 9560
i7-7700HQ
2.80GHz
4
16GB
3.7%
66 MB/s
Lenovo Thinkpad 20A7CTO
i7-4600U
2.10GHz
2
8GB
8.7%
53 MB/s
Asus X405UA
i3-7100U
2.40GHz
2
4GB
9.2%
46 MB/s
Samsung 90X3A
i5-2537M
1.40GHz
2
8GB
14.1%
31 MB/s
Asus X540SA
Pentium
N3700
1.60GHz
2
4GB
20.1%
22 MB/s
Table 10 Performance comparison of different PC specifications