svn commit: r313260 - head/sys/kern

[Ed Maste]

On 7 February 2017 at 10:30, Steven Hartland
<steven.hartland at multiplay.co.uk> wrote:
> All I'm suggesting is, while one could guess this may be a performance or
> possibly a compatibility thing, the reason is not obvious, so a small piece
> of detail on why the change was done should always be included.
>
> For this one something like the following would be nice:
>
> Switch fget_unlocked to atomic_fcmpset
>
> Improve performance under contention by switching fget_unlocked to
> use atomic_fcmpset.

I agree, and one of the key reasons to do this is so that there's this
tiny bit of context if someone later runs "git blame" or "svn
annotate" and discovers this change for the line containing
atomic_fcmpset. Comments containing "eliminate memory leak" or "remove
unused variable" have a self-evident reason, but I don't believe
that's true for "switch to atomic_fcmpset."

Repeating the "switch fget_unlocked to..." in the proposed commit
message above feels redundant to me though, and I would suggest:

| Switch fget_unlocked to atomic_fcmpset
|
| Improves performance under contention.

or just:

| Use atmoic_fcmpset to improve performance under contention