On 2014/11/25 13:30, Liu Bo wrote:
This is actually inspired by ZFS, who offers checksum functions ranging
from the simple-and-fast fletcher2 to the slower-but-secure sha256.
Back to btrfs, crc32c is the only choice.
And also for the slowness of sha256, Intel has a set of instructions for
it, "Intel SHA Extensions", that may help a lot.
I think the advantage will be in giving a choice with some strong
suggestions:
An example of suggestions - if using sha256 on an old or "low-power"
CPU, detect that the CPU doesn't support the appropriate acceleration
functions and print a warning at mount or a warning-and-prompt at mkfs-time.
The default could even be changed based on the architecture - though I
suspect crc32c is already a good default on most architectures.
The choice allowance gives flexibility where admins know it optimally
could be used - and David's suggestion (separate thread) would be able
to take advantage of that.
--
__________
Brendan Hide
http://swiftspirit.co.za/
http://www.webafrica.co.za/?AFF1E97
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