linux-kernel - Re: [PATCH 02/16] user_ns: use new hashtable implementation

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Date:	Sat, 18 Aug 2012 23:52:26 +0200
From:	Sasha Levin <levinsasha928@...il.com>
To:	"Eric W. Biederman" <ebiederm@...ssion.com>
CC:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Tejun Heo <tj@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 02/16] user_ns: use new hashtable implementation

On 08/15/2012 01:52 AM, Eric W. Biederman wrote:
> Sasha Levin <levinsasha928@...il.com> writes:
>> > Switch user_ns to use the new hashtable implementation. This reduces the amount of
>> > generic unrelated code in user_ns.
> Two concerns here.
> 1) When adding a new entry you recompute the hash where previously that
>    was not done.  I believe that will slow down adding of new entries.

Since the hashtable doesn't expose the internal hashing to the user of the
hashtable it would require adding a new interface to deal with in.

I don't feel that a whole new interface to optimize out something which is very
cheap (one multiplication + shift) in this case, I'd rather avoid having a new
interface.

Is it ok with you if I leave it as is in the next version of the patch?
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