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From: Herbert Xu <herbert@gondor.apana.org.au>
To: NeilBrown <neilb@suse.com>
Cc: Thomas Graf <tgraf@suug.ch>,
	netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 5/6] rhashtable: support guaranteed successful insertion.
Date: Wed, 28 Mar 2018 14:04:32 +0800	[thread overview]
Message-ID: <20180328060432.GA16291@gondor.apana.org.au> (raw)
In-Reply-To: <87y3id42zo.fsf@notabene.neil.brown.name>

On Wed, Mar 28, 2018 at 08:34:19AM +1100, NeilBrown wrote:
>
> It is easy to get an -EBUSY insertion failure when .disable_count is
> enabled, and I did get that.  Blindly propagating that up caused lustre
> to get terribly confused - not too surprising really.

Right, so this failure mode is specific to your patch 6.

I think I see the problem.  As it currently stands, we never
need growing when we hit the bucket length limit.  We only do
rehashes.

With your patch, you must change it so that we actually try to
grow the table if necessary when we hit the bucket length limit.

Otherwise it will result in the EBUSY that you're seeing.

I laso think that we shouldn't make this a toggle.  If we're going
to do disable_count then it should be unconditionally done for
everyone.

However, I personally would prefer a percpu elem count instead of
disabling it completely.  Would that be acceptable to your use-case?

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

  reply	other threads:[~2018-03-28  6:04 UTC|newest]

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-03-26 23:33 [PATCH 0/6] rhashtable: assorted fixes and enhancements NeilBrown
2018-03-26 23:33 ` [PATCH 1/6] rhashtable: improve documentation for rhashtable_walk_peek() NeilBrown
2018-03-27 10:55   ` Sergei Shtylyov
2018-03-27 15:30   ` Herbert Xu
2018-03-27 15:47   ` David Miller
2018-03-27 21:45   ` [PATCH 1/6 v2] " NeilBrown
2018-03-27 22:46   ` [PATCH 1/6] " Andreas Grünbacher
2018-03-28  0:49     ` NeilBrown
2018-03-26 23:33 ` [PATCH 3/6] rhashtable: reset intr when rhashtable_walk_start sees new table NeilBrown
2018-03-27 15:47   ` Herbert Xu
2018-03-26 23:33 ` [PATCH 6/6] rhashtable: allow element counting to be disabled NeilBrown
2018-03-26 23:33 ` [PATCH 5/6] rhashtable: support guaranteed successful insertion NeilBrown
2018-03-27 15:56   ` Herbert Xu
2018-03-27 21:34     ` NeilBrown
2018-03-28  6:04       ` Herbert Xu [this message]
2018-03-28  7:04         ` NeilBrown
2018-03-28  7:27           ` Herbert Xu
2018-03-28 21:26             ` NeilBrown
2018-03-29  5:22               ` Herbert Xu
2018-04-06  3:11                 ` NeilBrown
2018-04-06  4:13                   ` Herbert Xu
2018-03-26 23:33 ` [PATCH 4/6] rhashtable: allow a walk of the hash table without missing objects NeilBrown
2018-03-27 15:49   ` David Miller
2018-03-27 15:54     ` Herbert Xu
2018-03-27 21:50     ` NeilBrown
2018-03-27 15:51   ` Herbert Xu
2018-03-27 21:54     ` NeilBrown
2018-03-28  6:07       ` Herbert Xu
2018-03-28  7:17         ` NeilBrown
2018-03-28  7:30           ` Herbert Xu
2018-03-28 21:34             ` NeilBrown
2018-03-29  1:13               ` NeilBrown
2018-03-26 23:33 ` [PATCH 2/6] rhashtable: remove outdated comments about grow_decision etc NeilBrown

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