From: Daniel Borkmann <daniel@iogearbox•net>
To: Eric Dumazet <eric.dumazet@gmail•com>
Cc: David Laight <David.Laight@ACULAB•COM>,
"davem@davemloft•net" <davem@davemloft•net>,
"tgraf@suug•ch" <tgraf@suug•ch>,
"pablo@netfilter•org" <pablo@netfilter•org>,
"johunt@akamai•com" <johunt@akamai•com>,
"kaber@trash•net" <kaber@trash•net>,
"netdev@vger•kernel.org" <netdev@vger•kernel.org>
Subject: Re: [PATCH net 2/2] rhashtable: remove indirection for grow/shrink decision functions
Date: Wed, 25 Feb 2015 19:56:08 +0100 [thread overview]
Message-ID: <54EE1AC8.6060206@iogearbox.net> (raw)
In-Reply-To: <1424886096.5565.104.camel@edumazet-glaptop2.roam.corp.google.com>
On 02/25/2015 06:41 PM, Eric Dumazet wrote:
...
> There is no need to track number of elements, using either an atomic_t
> or percpu_counter. This adds unnecessary burden.
>
> 1) Automatic shrinking is a non issue. This will free very little
> memory, compared to previous peak usage (including objects put in
> rhashtable). If hash grown to a certain point, it's likely it will grow
> again later.
So you are saying that shrinking is most likely a rather undesirable
use-case in rhashtable?
> 2) Growing can be triggered when any bucket has more than X elems, and
> that is given for free at insert time.
> X could be log2(buckets)/2 I guess. (aka shift/2)
Yes, I think such a facility can be added easily.
> A global limit on number of elements should be controlled by rhashtable
> users - if needed -, not in the rhashtable itself.
Makes sense, thanks for the suggestion! I'll experiment with the above
per bucket tracking a bit if you're okay with that, and also unfiddle
the rht counter internals from netlink.
Thanks,
Daniel
next prev parent reply other threads:[~2015-02-25 18:56 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-02-25 15:31 [PATCH net 0/2] rhashtable updates Daniel Borkmann
2015-02-25 15:31 ` [PATCH net 1/2] rhashtable: unconditionally grow when max_shift is not specified Daniel Borkmann
2015-02-25 16:28 ` Thomas Graf
2015-02-25 16:36 ` Daniel Borkmann
2015-02-25 16:44 ` Daniel Borkmann
2015-02-25 17:09 ` Thomas Graf
2015-02-25 15:31 ` [PATCH net 2/2] rhashtable: remove indirection for grow/shrink decision functions Daniel Borkmann
2015-02-25 15:41 ` David Laight
2015-02-25 15:46 ` Daniel Borkmann
2015-02-25 15:51 ` David Laight
2015-02-25 16:14 ` Daniel Borkmann
2015-02-25 17:41 ` Eric Dumazet
2015-02-25 17:49 ` David Laight
2015-02-25 18:15 ` Eric Dumazet
2015-02-25 18:56 ` Daniel Borkmann [this message]
2015-02-25 19:52 ` Eric Dumazet
2015-02-25 20:10 ` Patrick McHardy
2015-02-26 10:02 ` tgraf
2015-02-27 22:30 ` David Miller
2015-02-28 0:48 ` Patrick McHardy
2015-02-28 1:35 ` David Miller
2015-02-26 14:18 ` David Laight
2015-03-11 6:42 ` Herbert Xu
2015-03-12 16:57 ` Thomas Graf
2015-03-13 7:06 ` Herbert Xu
2015-02-25 17:23 ` Thomas Graf
2015-02-27 21:06 ` [PATCH net 0/2] rhashtable updates David Miller
-- strict thread matches above, loose matches on Subject: below --
2015-02-25 22:09 [PATCH net 2/2] rhashtable: remove indirection for grow/shrink decision functions Alexei Starovoitov
2015-02-26 7:53 ` Patrick McHardy
2015-02-26 8:54 ` Daniel Borkmann
2015-02-26 14:50 ` Eric Dumazet
2015-02-26 14:54 ` Patrick McHardy
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