Subject: Re: should I hashinit desiredvnodes or a fraction of it?
To: VaX#n8 <firstname.lastname@example.org>
From: Bill Studenmund <email@example.com>
Date: 06/02/2004 17:43:33
Content-Type: text/plain; charset=us-ascii
On Wed, Jun 02, 2004 at 04:11:27PM -0400, VaX#n8 wrote:
> Some file systems seem to allocate (via hashinit) one hash bucket
> for every desired vnode, (isn't that wasteful?), others some fraction
> of that. Some file systems, like fdesc, allocate a fixed number
> (in TCFS, merely 16!), which seems undesirable. What should TCFS
> allocate? Consensus would seem to suggest desiredvnodes.
No, because then you aren't hashing. I'd say start with sixteen, or one=20
sixteenth of desiredvnodes.
It is especially wasteful as if you're using layered vnodes, you will=20
never have more than half of desiredvnodes in your hash table.
You also can change the value later.
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