lingon
Posts: 157
Joined: Fri Aug 26, 2011 7:31 am

Memory performance with kernel 3.12.30+ #717 has increased

Mon Oct 27, 2014 3:29 pm

The changelog for the firmware update that comes with kernel 3.12.30+ #717 says:
"kernel: Improve __copy_to_user and __copy_from_user performance
Provide a __copy_from_user that uses memcpy. On BCM2708, use
optimised memcpy/memmove/memcmp/memset implementations."

This update gives a significant performance boost to the memory system. On a Raspberry Pi running at 1 GHz with turbo overclocking I can get for the very first time cached reads above 300 MB/s from hdparm. Previously I have seen a result slightly above 230 MB/s at best. As this has been optimized already earlier I did not expect so large gains still to be achieved! Thank you very much! :D

Code: Select all

hdparm -Tt /dev/mmcblk0p2

/dev/mmcblk0p2:
 Timing cached reads:   674 MB in  2.00 seconds = 336.59 MB/sec
 Timing buffered disk reads:  54 MB in  3.09 seconds =  17.47 MB/sec

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