Timings are represented as <extract> + <install> where:
<extract>- time in seconds to untar/gunzip thetarorimg.gzfile, and store the resulting content<install>- time in seconds to copySYSTEM,KERNELand - for RPi - bootloader files to/flash
The RPi3+ <extract> and <install> times are highly variable when writing to /flash and /storage, which may suggest an issue with my RPi3+ hardware, SD card, or a kernel/driver bug (or some combination of all three). The total time to upgrade the RPi3+ via tar file can vary by as much as 80 seconds. We don't see this issue when extacting to tmpfs, but it is seen when installing to /flash, which might suggest a performance issue when writing to the SD card.
We currently use dd with bs=1M (and conv=fsync) to transfer data to /flash, I wonder if we can do better here - something for later.