Date: Thu, 24 Apr 1997 20:49:14 +0900 (JST) From: Michael Hancock <michaelh@cet.co.jp> To: Poul-Henning Kamp <phk@dk.tfs.com> Cc: fs@freebsd.org Subject: Re: the namei cache... Message-ID: <Pine.SV4.3.95.970424202555.13551A-100000@parkplace.cet.co.jp> In-Reply-To: <801.861878478@critter>
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On Thu, 24 Apr 1997, Poul-Henning Kamp wrote:
> >With hashing you can work on the hashing algorithm. Btw, what is the hash
> >key now? vp+name[20]?
>
> directory vnode v_id + the regular namei hash.
It's hard to tell how well keys are distributed. The cn_hash component
seems like it can be improved, maybe by taking only 3 or 4 of the
characters in the name and then doing some shifts and xor's on them.
cnp->cn_hash = 0;
for (cp = cnp->cn_nameptr; *cp != 0 && *cp != '/'; cp++)
cnp->cn_hash += (unsigned char)*cp;
cnp->cn_namelen = cp - cnp->cn_nameptr;
if (cnp->cn_namelen > NAME_MAX) {
error = ENAMETOOLONG;
goto bad;
}
Regarding the capability have you done any analysis on it's distribution?
Mike
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