From: Tejun Heo <tj@kernel•org>
To: Sasha Levin <levinsasha928@gmail•com>
Cc: torvalds@linux-foundation•org, akpm@linux-foundation•org,
linux-kernel@vger•kernel.org, linux-mm@kvack•org,
paul.gortmaker@windriver•com, davem@davemloft•net,
rostedt@goodmis•org, mingo@elte•hu, ebiederm@xmission•com,
aarcange@redhat•com, ericvh@gmail•com, netdev@vger•kernel.org,
josh@joshtriplett•org, eric.dumazet@gmail•com,
mathieu.desnoyers@efficios•com, axboe@kernel•dk, agk@redhat•com,
dm-devel@redhat•com, neilb@suse•de, ccaulfie@redhat•com,
teigland@redhat•com, Trond.Myklebust@netapp•com,
bfields@fieldses•org, fweisbec@gmail•com, jesse@nicira•com,
venkat.x.venkatsubra@oracle•com, ejt@redhat•com,
snitzer@redhat•com, edumazet@google•com,
linux-nfs@vger•kernel.org, dev@openvswitch•org,
rds-devel@oss•oracle.com, lw@cn•fujitsu.com
Subject: Re: [PATCH v3 01/17] hashtable: introduce a small and naive hashtable
Date: Thu, 23 Aug 2012 13:04:56 -0700 [thread overview]
Message-ID: <20120823200456.GD14962@google.com> (raw)
In-Reply-To: <50357840.5020201@gmail.com>
Hello, Sasha.
On Thu, Aug 23, 2012 at 02:24:32AM +0200, Sasha Levin wrote:
> > I think the almost trivial nature of hlist hashtables makes this a bit
> > tricky and I'm not very sure but having this combinatory explosion is
> > a bit dazzling when the same functionality can be achieved by simply
> > combining operations which are already defined and named considering
> > hashtable. I'm not feeling too strong about this tho. What do others
> > think?
>
> I'm thinking that this hashtable API will have 2 purposes: First, it would
> prevent the excessive duplication of hashtable implementations all around the code.
>
> Second, it will allow more easily interchangeable hashtable implementations to
> find their way into the kernel. There are several maintainers who would be happy
> to see dynamically sized RCU hashtable, and I'm guessing that several more
> variants could be added based on needs in specific modules.
>
> The second reason is why several things you've mentioned look the way they are:
>
> - No DEFINE_HASHTABLE(): I wanted to force the use of hash_init() since
> initialization for other hashtables may be more complicated than the static
> initialization for this implementation, which means that any place that used
> DEFINE_HASHTABLE() and didn't do hash_init() will be buggy.
I think this is problematic. It looks exactly like other existing
DEFINE macros yet what its semantics is different. I don't think
that's a good idea.
> I'm actually tempted in hiding hlist completely from hashtable users, probably
> by simply defining a hash_head/hash_node on top of the hlist_ counterparts.
I think that it would be best to keep this one simple & obvious, which
already has enough in-kernel users to justify its existence. There
are significant benefits in being trivially understandable and
expectable. If we want more advanced ones - say resizing, hybrid or
what not, let's make that a separate one. No need to complicate the
common straight-forward case for that.
So, I think it would be best to keep this one as straight-forward and
trivial as possible. Helper macros to help its users are fine but
let's please not go for full encapsulation.
Thanks.
--
tejun
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next prev parent reply other threads:[~2012-08-23 20:04 UTC|newest]
Thread overview: 67+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-08-22 2:26 [PATCH v3 00/17] generic hashtable implementation Sasha Levin
2012-08-22 2:26 ` [PATCH v3 02/17] userns: use new " Sasha Levin
[not found] ` <1345602432-27673-1-git-send-email-levinsasha928-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2012-08-22 2:26 ` [PATCH v3 01/17] hashtable: introduce a small and naive hashtable Sasha Levin
[not found] ` <1345602432-27673-2-git-send-email-levinsasha928-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2012-08-22 18:01 ` Tejun Heo
2012-08-22 23:54 ` Ryan Mallon
2012-08-23 0:24 ` Sasha Levin
2012-08-23 20:04 ` Tejun Heo [this message]
2012-08-24 19:47 ` Sasha Levin
[not found] ` <5037DA47.9010306-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2012-08-24 19:59 ` Tejun Heo
[not found] ` <20120824195941.GC21325-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
2012-08-24 20:11 ` Sasha Levin
[not found] ` <5037E00B.6090606-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2012-08-24 20:33 ` Tejun Heo
[not found] ` <20120824203332.GF21325-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
2012-08-24 20:53 ` Sasha Levin
2012-08-24 21:23 ` Tejun Heo
[not found] ` <20120824212348.GK21325-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
2012-08-24 22:59 ` Sasha Levin
2012-08-24 23:07 ` Tejun Heo
2012-08-25 4:24 ` Mathieu Desnoyers
2012-08-28 9:56 ` Sasha Levin
2012-08-28 10:11 ` Mathieu Desnoyers
2012-08-28 11:27 ` Sasha Levin
[not found] ` <503CAB1E.5010408-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2012-08-28 11:56 ` Mathieu Desnoyers
2012-08-28 23:00 ` Mathieu Desnoyers
2012-09-04 15:35 ` Steven Rostedt
[not found] ` <1346772948.27919.9.camel-f9ZlEuEWxVcJvu8Pb33WZ0EMvNT87kid@public.gmane.org>
2012-09-04 16:30 ` Pedro Alves
2012-09-04 16:40 ` Pedro Alves
[not found] ` <50462EE8.1090903-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2012-09-04 17:01 ` Mathieu Desnoyers
2012-09-06 13:53 ` Sasha Levin
2012-09-06 14:19 ` Pedro Alves
[not found] ` <5048AAF6.5090101-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2012-09-06 14:33 ` Mathieu Desnoyers
2012-09-06 14:36 ` David Laight
2012-09-06 14:55 ` Josh Triplett
2012-09-06 15:11 ` Steven Rostedt
2012-09-06 15:49 ` Sasha Levin
[not found] ` <5048C615.4070204-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2012-09-06 16:00 ` Steven Rostedt
[not found] ` <1346947206.1680.36.camel-f9ZlEuEWxVcJvu8Pb33WZ0EMvNT87kid@public.gmane.org>
2012-09-06 16:21 ` Sasha Levin
[not found] ` <5048CDA2.10300-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2012-09-06 16:50 ` Mathieu Desnoyers
2012-09-06 17:01 ` Sasha Levin
[not found] ` <5048D6DE.8090805-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2012-09-06 17:02 ` Mathieu Desnoyers
2012-09-06 17:15 ` Steven Rostedt
2012-09-04 17:17 ` Steven Rostedt
2012-09-04 17:21 ` Pedro Alves
[not found] ` <50463883.8080706-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2012-09-04 20:59 ` Steven Rostedt
2012-09-04 21:51 ` Pedro Alves
[not found] ` <504677C8.3050801-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2012-09-04 22:41 ` Steven Rostedt
2012-09-04 22:58 ` Pedro Alves
[not found] ` <50468778.5000207-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2012-09-04 23:27 ` Steven Rostedt
2012-09-04 16:32 ` Mathieu Desnoyers
2012-08-22 2:26 ` [PATCH v3 03/17] mm, ksm: use new hashtable implementation Sasha Levin
2012-08-22 2:26 ` [PATCH v3 04/17] workqueue: " Sasha Levin
[not found] ` <1345602432-27673-5-git-send-email-levinsasha928-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2012-08-22 18:05 ` Tejun Heo
2012-08-22 2:27 ` [PATCH v3 05/17] mm/huge_memory: " Sasha Levin
2012-08-22 2:27 ` [PATCH v3 07/17] net, 9p: " Sasha Levin
2012-08-22 2:27 ` [PATCH v3 08/17] block, elevator: " Sasha Levin
2012-08-22 2:27 ` [PATCH v3 09/17] SUNRPC/cache: " Sasha Levin
2012-08-22 2:27 ` [PATCH v3 10/17] dlm: " Sasha Levin
2012-08-22 2:27 ` [PATCH v3 13/17] lockd: " Sasha Levin
2012-08-22 11:47 ` J. Bruce Fields
[not found] ` <20120822114752.GC20158-uC3wQj2KruNg9hUCZPvPmw@public.gmane.org>
2012-08-22 12:13 ` Sasha Levin
2012-08-22 13:12 ` J. Bruce Fields
[not found] ` <5034CD02.2010103-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2012-08-22 13:22 ` Mathieu Desnoyers
2012-08-22 17:32 ` Sasha Levin
2012-08-22 2:27 ` [PATCH v3 16/17] tracing output: " Sasha Levin
2012-08-22 2:27 ` [PATCH v3 17/17] SUNRPC: use new hashtable implementation in auth Sasha Levin
2012-08-22 2:27 ` [PATCH v3 06/17] tracepoint: use new hashtable implementation Sasha Levin
2012-08-22 2:27 ` [PATCH v3 11/17] net,l2tp: " Sasha Levin
2012-08-22 2:27 ` [PATCH v3 12/17] dm: " Sasha Levin
2012-08-22 2:27 ` [PATCH v3 14/17] net,rds: " Sasha Levin
2012-08-22 2:27 ` [PATCH v3 15/17] openvswitch: " Sasha Levin
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