In message <[EMAIL PROTECTED]>, Matt Dillon writes:
>:>:> scaleability.
>:>:
>:>:Uhm, that is actually not true.
>:>:
>:>:We keep namecache entries around as long as we can use them, and that
>:>:generally means that recreating them is a rather expensive operation,
>:>:involving creation of vnode and very likely a vm object again.
>:>
>:> The vnode cache is a different cache. positive namei hits will
>:> reference a vnode, but namei elements can be flushed at any
>:> time without flushing the underlying vnode.
>:
>:Right, but doing so means that to refind that vnode from the name
>:is (comparatively) very expensive.
>:
>:--
>:Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
>:[EMAIL PROTECTED] | TCP/IP since RFC 956
>
> The only thing that is truely expensive is having to physically
> scan a large directory in order to instantiate a new namei
> record. Everything else is inexpensive by comparison (by two
> orders of magnitude!), even constructing new vnodes.
>
> Without vmiodirenable turned on, any directory [...]
It's worse than that, we are still way too rude in throwing away
directory data...
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
[EMAIL PROTECTED] | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
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