powerpc: reduce number of WATCHDOG_RESET calls from flush_cache
Calling WATCHDOG_RESET for each and every cache line is overkill. In our case, the kernel image is a little over 7MB, and the almost 500000 calls of WATCHDOG_RESET() adds about one second to the boottime. I very highly doubt there's any real hardware where flushing 64K from cache to memory takes more than a few milliseconds, so this should be completely safe. Since it reduces the number of WATCHDOG_RESET() calls by roughly a factor of 1000, the overhead from those is practically eliminated. (Just in case the range flushed is so small that it doesn't cross a 64K boundary, add a single WATCHDOG_RESET() between the loops). 64K is chosen because that's also the default chunk size used by the hashing algorithms, and when, say, a sha256 digest of a kernel image of a few MB is being verified, that's almost guaranteed to be cache-cold, so apart from the computations being done, the hashing is also bounded by memory speed - so if 64K works for those cases, it should certainly also work when memory access is the only thing being done. Signed-off-by:Rasmus Villemoes <rasmus.villemoes@prevas.dk> Reviewed-by:
Stefan Roese <sr@denx.de> Reviewed-by:
Priyanka Jain <priyanka.jain@nxp.com>
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