We even have a working hcreate(3) and friends in 5.0-CURRENT,
that could probably be tried as well.  Will MFC shortly.

On Fri, Sep 28, 2001 at 08:23:29AM +0200, Poul-Henning Kamp wrote:
> In message <[EMAIL PROTECTED]>, Julian Elischer writes:
> >This is a multi-part message in MIME format.
> >--------------5937F02517145C712E28C299
> >Content-Type: text/plain; charset=us-ascii
> >Content-Transfer-Encoding: 7bit
> >
> >'du' keeps an array of files it has encountered that have > 1 link.
> >Whenever it encounters another, it checks to see if it's one it has
> >already seen
> >and thus can avoid counting its space twice..
> >
> >This is ok for small filesystems, however VICOR maintains
> >500GB filesystems on which much of the data has several links.
> >
> >The following patch to replace the linear array (which it realocs if too
> >small)
> >(which it scans linearly) with a hash-table can makle a DRASTIC change
> >to how DU perfomrs for us in this environment.
> >
> >In a small test, we made a linked copy of /usr/src
> >
> >the run times were:
> >old: 0.410u 2.221s 1:55.41 2.2%      12+1355k 6325+0io 2pf+0w
> >new: 8.610u 2.665s 2:09.23 8.7%      10+718k 6367+0io 2pf+0  
> Have you examined if the hask key is evenly distributed ?
> >Does anyone have objections to me committing this (or a variant of it)?
> I would certainly have objections of you show us one patch and 
> commit another..
> >  *  The Regents of the University of California.  All rights reserved.
> >  *
> >+ * This version of du has been modified by Andre de Bruin and Scott Macy for Vicor.
> Too long line ?
> >+ * The change is related to the handling of file links, in the official
> >+ * release, du keeps a simple linked list of all visited i-nodes with
> >+ * multiple links. This list is now implemented as a "hash table" (actually
> >+ * a fixed size array) with link list nodes providing a 
> >+ * performance of up to 30% better than the original version.
> >+ * The only changes are in file create.c and marked with "AdB".
> We put such stuff in the CVS commit message, not in the source file.
> >+typedef struct _ID {
> >+    dev_t       dev;
> >+    ino_t       inode;
> >+        struct _ID *next;
> >+} ID;
> Why not use db(3) ?
> It has a known good hash, it autosizes to different task-sets and
> it could be setup with an option to put the hash-table in a diskfile
> ("du -t" ?) for known bad cases of many hardlinks

Ruslan Ermilov          Oracle Developer/DBA,
[EMAIL PROTECTED]           Sunbay Software AG,
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+380.652.512.251        Simferopol, Ukraine

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