From: Richard Kennedy <richard@rsk.demon.co.uk>
To: Eric Dumazet <eric.dumazet@gmail.com>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
lkml <linux-kernel@vger.kernel.org>,
Dipankar Sarma <dipankar@in.ibm.com>
Subject: Re: [PATCH] RCU: remove alignment padding from rcu_data on 64 bit builds
Date: Fri, 06 May 2011 13:13:56 +0100 [thread overview]
Message-ID: <1304684036.1998.10.camel@castor.rsk> (raw)
In-Reply-To: <1304662845.3131.23.camel@edumazet-laptop>
On Fri, 2011-05-06 at 08:20 +0200, Eric Dumazet wrote:
...
> We could shrink this structure more, converting some 64bit fields to
> 32bit ones.
>
> Rationale is the algo is working well on 32bit arches, no need to use
> 64bit fields.
>
> candidates : completed, gpnum, passed_quiesc_completed, qlen,
> qlen_last_fqs_check, blimit.
>
> Counters might be converted too.
I don't know the code well enough to make that decision ;)
Is it possible to shrink it enough to free up another cache line ?
(16 longs to ints).
CONFIG_NO_HZ adds 24 bytes so even for users with !CONFIG_NO_HZ the
variables you suggest are not enough to free a cache line.
regards
Richard
next prev parent reply other threads:[~2011-05-06 12:14 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-05-05 15:50 [PATCH] RCU: remove alignment padding from rcu_data on 64 bit builds Richard Kennedy
2011-05-06 6:20 ` Eric Dumazet
2011-05-06 12:13 ` Richard Kennedy [this message]
2011-05-08 14:53 ` Paul E. McKenney
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