Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Date:   Wed, 12 Dec 2018 16:00:37 +0800
From:   Herbert Xu <herbert@gondor.apana.org.au>
To:     NeilBrown <neilb@suse.com>
Cc:     Thomas Graf <tgraf@suug.ch>, Tom Herbert <tom@quantonium.net>,
        David Miller <davem@davemloft.net>, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH net-next] rhashtable: further improve stability of
 rhashtable_walk
Message-ID: <20181212080037.j2zs22t57uxdu2jr@gondor.apana.org.au>
References: <153086101070.2825.6850140624411927465.stgit@noble>
 <153086109256.2825.15329014177598382684.stgit@noble>
 <87zhtkeimx.fsf@notabene.neil.brown.name>
 <20181207053943.7zacyn5uvqkfnfoi@gondor.apana.org.au>
 <87k1kico1o.fsf@notabene.neil.brown.name>
 <20181211051755.modgomqzszkbiihe@gondor.apana.org.au>
 <87mupbvch0.fsf@notabene.neil.brown.name>
 <20181212054601.wbzpxjunnsfi62mz@gondor.apana.org.au>
 <87efanuu06.fsf@notabene.neil.brown.name>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <87efanuu06.fsf@notabene.neil.brown.name>
User-Agent: NeoMutt/20170113 (1.7.2)
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Wed, Dec 12, 2018 at 05:41:29PM +1100, NeilBrown wrote:
>
> So you would substantially slow down the rhashtable_walk_start() step.

This whole thing is meant for uses such as /proc and netlink
enumeration.  Speed is definitely not a prerogative of these
iterators.

For that matter, if speed was an issue then surely you would
not drop out of the RCU read lock at all while iterating.

It sounds to me like you're trying to use this interface for
something that it's simply not designed to do.

Cheers,
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt