Performance measurements
QNX SDP8.0TechnotesDeveloperUser
The following table shows the boot time savings using IFS Restoration, as measured on an EDOSK7780 at 400 MHz. Note that debug output is disabled.
| Restoration type | Image size | IFS compression | IFS checksum | Initial boot time | Subsequent boot time | Savings |
|---|---|---|---|---|---|---|
| Kernel | 32.8 MB | UCL | No | 8 s | < 0.5 s | 7.5 s |
| Kernel | 32.8 MB | UCL | Yes | 8 s | < 1.0 s | 7.0 s |
| Kernel | 32.8 MB | None | No | 7 s | < 0.5 s | 6.5 s |
| Kernel | 32.8 MB | None | Yes | 7 s | < 1.0 s | 6.0 s |
| Secondary IFS | 32.0 MB (0.2 MB, 31.8 MB) | UCL (primary)
None (secondary) |
No | 7 s | < 0.5 s | 6.5 s |
| Secondary IFS | 32.0 MB (0.2 MB, 31.8 MB) | UCL (primary)
None (secondary) |
Yes | 7 s | < 1.0 s | 6.0 s |
Note the following details regarding these performance numbers:
- Boot times don't include the time from power-on/reset vector but from the point where the IPL scans and loads the image (add 10–50 ms to the times above).
- During initial boot, images are manually copied from flash to RAM (i.e. no DMA).
- Boot times include the time to:
- copy the image from flash to RAM (on initial boot)
- run the startup and initialize the kernel
- start the serial driver and the shell
- Boot times don't include the time to start other drivers or user applications.
- Time measurements are made to approximately 0.5 second granularity (subsequent boot times are likely faster than reported).
- Boot time savings for uncompressed images are less because the initial booting is faster than UCL compressed images (due to the time it takes to uncompress the UCL image).
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