From: Thomas Graf <tgraf@suug.ch>
To: Herbert Xu <herbert@gondor.apana.org.au>
Cc: "David S. Miller" <davem@davemloft.net>,
Eric Dumazet <eric.dumazet@gmail.com>,
Patrick McHardy <kaber@trash.net>,
Josh Triplett <josh@joshtriplett.org>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
netdev@vger.kernel.org
Subject: Re: [v3 PATCH 9/9] rhashtable: Add immediate rehash during insertion
Date: Mon, 23 Mar 2015 21:56:32 +0000 [thread overview]
Message-ID: <20150323215632.GA22099@casper.infradead.org> (raw)
In-Reply-To: <20150323214422.GA19938@gondor.apana.org.au>
On 03/24/15 at 08:44am, Herbert Xu wrote:
> I specifically made it this way because I don't think the users
> should be touching the actual limit. This is something that you
> always want to enable unless you're in the situation of netfilter
> where you don't care.
>
> If you did care then 16 is sort of intrinsic to the 32-bit hash
> that we're using. Going below doesn't make much sense because
> you may run into false warnings due to double rehashes (that's
> how I discovered 4 was uesless, very quickly :) Remember the
> rehash is only there to detect pathological cases where people
> are actively attacking us. Otherwise the 100% utilisation check
> will kick in.
>
> Going above 16 means that you're hashing multiple objects with
> the same key. Then you'd want to disable this altogether.
>
> The rhashtable already has too many knobs and I don't want to
> add anything unnecessary to rhashtable_params.
OK. I can certinaly live with this. You are certinaly right that
simplicity isn't a bad move here. Thanks for being patience and
answering all the questions.
Acked-by: Thomas Graf <tgraf@suug.ch>
next prev parent reply other threads:[~2015-03-23 21:56 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-03-23 13:49 [v3 PATCH 0/9] rhashtable: Multiple rehashing Herbert Xu
2015-03-23 13:50 ` [v3 PATCH 1/9] rhashtable: Add barrier to ensure we see new tables in walker Herbert Xu
2015-03-23 13:50 ` [v3 PATCH 2/9] rhashtable: Eliminate unnecessary branch in rht_key_hashfn Herbert Xu
2015-03-23 13:58 ` Thomas Graf
2015-03-23 13:50 ` [v3 PATCH 3/9] rhashtable: Allow hashfn to be unset Herbert Xu
2015-03-23 15:36 ` Thomas Graf
2015-03-23 13:50 ` [v3 PATCH 4/9] netlink: Use default rhashtable hashfn Herbert Xu
2015-03-23 13:50 ` [v3 PATCH 5/9] tipc: " Herbert Xu
2015-03-23 13:50 ` [v3 PATCH 6/9] rhashtable: Shrink to fit Herbert Xu
2015-03-23 15:38 ` Thomas Graf
2015-03-23 13:50 ` [v3 PATCH 7/9] rhashtable: Add multiple rehash support Herbert Xu
2015-03-23 16:37 ` Thomas Graf
2015-03-23 13:50 ` [v3 PATCH 8/9] rhashtable: Allow GFP_ATOMIC bucket table allocation Herbert Xu
2015-03-23 16:38 ` Thomas Graf
2015-03-23 13:50 ` [v3 PATCH 9/9] rhashtable: Add immediate rehash during insertion Herbert Xu
2015-03-23 16:50 ` Thomas Graf
2015-03-23 16:54 ` David Laight
2015-03-23 21:44 ` Herbert Xu
2015-03-23 21:56 ` Thomas Graf [this message]
2015-03-23 22:15 ` Herbert Xu
2015-03-24 2:09 ` [v3 PATCH 0/9] rhashtable: Multiple rehashing David Miller
2015-03-24 2:37 ` Herbert Xu
2015-03-24 18:57 ` David Miller
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