netdev - Re: [net-next PATCH V2 8/9] net: frag queue locking per hash bucket

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Message-ID: <1354208920.14302.1907.camel@edumazet-glaptop>
Date:	Thu, 29 Nov 2012 09:08:40 -0800
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Jesper Dangaard Brouer <brouer@...hat.com>
Cc:	"David S. Miller" <davem@...emloft.net>,
	Florian Westphal <fw@...len.de>, netdev@...r.kernel.org,
	Pablo Neira Ayuso <pablo@...filter.org>,
	Thomas Graf <tgraf@...g.ch>, Cong Wang <amwang@...hat.com>,
	Patrick McHardy <kaber@...sh.net>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	Herbert Xu <herbert@...dor.hengli.com.au>
Subject: Re: [net-next PATCH V2 8/9] net: frag queue locking per hash bucket

On Thu, 2012-11-29 at 17:15 +0100, Jesper Dangaard Brouer wrote:
> This patch implements per hash bucket locking for the frag queue
> hash.  This removes two write locks, and the only remaining write
> lock is for protecting hash rebuild.  This essentially reduce the
> readers-writer lock to a rebuild lock.

So we still have this huge contention on the reader-writer lock cache
line...

I would just remove it. (And remove hash rebuild, or make it RCU
compatible )


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