Continuing my catchup on recent commits, there’s now a ‘version 7’ internal to HAMMER 1. It changes the CRC code to a faster version, but since this instruction isn’t used (yet), there’s no real world impact. Remember this for next time you want to run ‘hammer version-upgrade’.
5 Replies to “HAMMER version 7”
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Why is development still being done on hammer1 (with the expedition of big fixes and security issue)?
Should all file system efforts be spent on hammer2?
Adam…
Because most of us are still using H1 and it is a stable, robust filesystem that still continues to see nice improvements. I for one am very appreciative of the new CRC code. It makes SSD-based systems (or large RAID arrays) that much more performant.
I’m confused by the commit message.
It says:
“Add support for version 7 which changes the CRC mechanic from the old slow CRC code to the faster ISCSI CRC code. ***We don’t use the CRC instruction yet***”
(Emphasis is mine.)
So the commit message says they are changing the slow CRC code to faster ISCSI CRC code … but then they say they don’t use CRC yet?
How can you change something that isn’t used yet?
You can change code that is not executed.
Modern CPUs have a hardware crc32 instruction.
Matt probably didn’t want to use it to preserve compatibility with previous machines.