Re: Testing 7.0 Beta: FFS still very slow when creating files

[Joerg Sonnenberger <joerg%britannica.bec.de@localhost>]

On Mon, Aug 25, 2014 at 09:09:24PM +0000, Taylor R Campbell wrote:
>    Date: Mon, 25 Aug 2014 20:02:44 +0200
>    From: "J. Hannken-Illjes" <hannken%eis.cs.tu-bs.de@localhost>
> 
>    Short answer: it is -- reverting external/gpl3/gcc/dist/gcc/builtins.c
>    from Rev. 1.3 to 1.2 brings back the old times which are the same as
>    they were on NetBSD 6.
> 
>    Given that this test has many calls to ufs_lookup/cache_lookup using
>    memcmp to check for equal filenames this is not a surprise.
> 
>    A rather naive "implementation" of memcmp (see below) drops the running
>    time from ~15 sec to ~9 secs.  We should consider improving our memcmp.
> 
> Sounds reasonable to me, although it looks like GCC's old builtin
> memcmp expansion actually failed to implement our specification: it
> returns -1, 0, or +1, like your patch, rather than the difference of
> the first differing bytes or zero as our man page specifies.  For most
> uses it doesn't matter, of course, but we ought to make sure to follow
> our own specification.

memcmp is only supposed to provide the correct sign, not the difference.

Joerg