FreeCalypso > hg > freecalypso-tools
comparison doc/Loadtools-performance @ 613:ab4021fb1c66
doc/Loadtools-performance: flash programming added
| author | Mychaela Falconia <falcon@freecalypso.org> |
|---|---|
| date | Mon, 24 Feb 2020 22:30:00 +0000 |
| parents | c847d742ab38 |
| children | 39b74c39d914 |
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| 612:52980e3a51c7 | 613:ab4021fb1c66 |
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| 16 programming and fc-xram loading operations are quite different in that their | 16 programming and fc-xram loading operations are quite different in that their |
| 17 run times do depend on the host system and USB-serial adapter or other serial | 17 run times do depend on the host system and USB-serial adapter or other serial |
| 18 port hardware - this host system dependency exists because of the way these | 18 port hardware - this host system dependency exists because of the way these |
| 19 operations are implemented in our architecture. | 19 operations are implemented in our architecture. |
| 20 | 20 |
| 21 Here is one example of expected flash programming time: flashing a FreeCalypso | |
| 22 Magnetite hybrid fw image (2378084 bytes) into an FCDEV3B board (S71PL129N | |
| 23 flash chip) via an FT2232D adapter at 812500 baud takes 2m11s on the Mother's | |
| 24 Slackware 14.2 system. This time is just for the flash program-bin operation, | |
| 25 not counting the flash erase which must be done first. Flash erase times are | |
| 26 determined entirely by physical processes inside the flash chip and are not | |
| 27 affected by software design or the serial link: for each sector to be erased, | |
| 28 fc-loadtool issues the sector erase command to the flash chip and then polls | |
| 29 the chip for operation completion status; the polling is done over the serial | |
| 30 link and thus may seem very slow, but the extra bit of latency added by the | |
| 31 finite polling speed is still negligible compared to the time of the actual | |
| 32 sector erase operation inside the flash chip. In contrast, the execution time | |
| 33 of a flash program-bin operation is a sum of 3 components: | |
| 34 | |
| 35 * The time it takes for the bits to be transferred over the serial link; | |
| 36 * The time it takes for the flash programming operation to complete on the | |
| 37 target (physics inside the flash chip); | |
| 38 * The overhead of command-response exchanges between fc-loadtool and loadagent. | |
| 39 | |
| 21 [To be continued] | 40 [To be continued] |