From: Thomas Graf <tgraf@suug.ch>
To: Herbert Xu <herbert@gondor.apana.org.au>
Cc: David Miller <davem@davemloft.net>, netdev@vger.kernel.org
Subject: Re: [PATCH net-next v2] rhashtable: Warn if min_size or max_size are not a power of two
Date: Thu, 19 Mar 2015 21:15:46 +0000 [thread overview]
Message-ID: <20150319211546.GA4190@casper.infradead.org> (raw)
In-Reply-To: <20150319210239.GB9601@gondor.apana.org.au>
On 03/20/15 at 08:02am, Herbert Xu wrote:
> On Thu, Mar 19, 2015 at 07:46:08PM +0000, Thomas Graf wrote:
> > The current code correctly limits table size to the next power of two.
> > This check is solely to catch programming errors.
> >
> > Signed-off-by: Thomas Graf <tgraf@suug.ch>
>
> I don't see the point of this. A maximum size of 3 says that
> the table size should never exceed 3 which makes perfect sense.
> And our current code will respect that.
>
> So why force it to be a power of 2 just because our table sizes
> happen to be powers of 2?
rht_grow_above_75() checks the old table size:
(!ht->p.max_size || tbl->size < ht->p.max_size);
If you specify max_size = 3, it grows the table to tbl->size = 4.
This can be avoided if max_size is a power of two.
next prev parent reply other threads:[~2015-03-19 21:15 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-03-19 16:34 [PATCH net-next] rhashtable: Warn if min_size or max_size are not a power of two Thomas Graf
2015-03-19 19:24 ` David Miller
2015-03-19 19:46 ` [PATCH net-next v2] " Thomas Graf
2015-03-19 21:02 ` Herbert Xu
2015-03-19 21:15 ` Thomas Graf [this message]
2015-03-19 21:49 ` Herbert Xu
2015-03-19 22:02 ` Herbert Xu
2015-03-19 22:31 ` [PATCH net-next] rhashtable: Round up/down min/max_size to ensure we respect limit Thomas Graf
2015-03-19 22:41 ` Herbert Xu
2015-03-20 1:02 ` David Miller
2015-03-20 10:57 ` [PATCH net-next v2] rhashtable: Warn if min_size or max_size are not a power of two David Laight
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