Re: NCHNAMLEN vnode cache limitation removal

[Jason Thorpe <thorpej%me.com@localhost>]

> On Sep 11, 2019, at 11:53 AM, Robert Elz <kre%munnari.OZ.AU@localhost> wrote:
> 
>    Date:        Wed, 11 Sep 2019 09:43:18 +0300
>    From:        Jason Thorpe <thorpej%me.com@localhost>
>    Message-ID:  <F435B615-E3E4-4ADF-B2AC-854A5C99D5E8%me.com@localhost>
> 
>  | Another advantage of de-duping the name strings is that you can
>  | compare names by testing pointer equivalence.
> 
> That works only if string you're comparing against the cache entry
> is itself a cache entry, which would mean a whole new data struct
> to make lookup of those strings fast (as it is now, comparisons get
> a pointer to the string in the cache, and simply compare it with the
> lookup string .. only insert (which is relatively rare) would need to
> search the string cache to see if a name is already there, so that can
> use a slow algorithm, with no extra data struct to manage.

True, you'd have to "create a de-dup'd string" to compare it to other de-dup'd strings using the pointer-equivalence method.  There's probably a string length threshold where that makes sense to do, and below that where it doesn't.

-- thorpej