From: Balbir Singh <balbir@linux.vnet.ibm.com>
To: Christoph Lameter <cl@linux.com>
Cc: Michael Holzheu <holzheu@linux.vnet.ibm.com>,
akpm@linux-foundation.org, Pekka Enberg <penberg@cs.helsinki.fi>,
linux-kernel@vger.kernel.org,
Eric Dumazet <eric.dumazet@gmail.com>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Tejun Heo <tj@kernel.org>,
linux-mm@kvack.org
Subject: Re: [thisops uV3 08/18] Taskstats: Use this_cpu_ops
Date: Mon, 6 Dec 2010 20:02:56 +0530 [thread overview]
Message-ID: <20101206143256.GE3158@balbir.in.ibm.com> (raw)
In-Reply-To: <alpine.DEB.2.00.1012011212490.3774@router.home>
* Christoph Lameter <cl@linux.com> [2010-12-01 12:13:44]:
> On Wed, 1 Dec 2010, Michael Holzheu wrote:
>
> > > return -ENOMEM;
> > >
> > > if (!info) {
> > > - int seq = get_cpu_var(taskstats_seqnum)++;
> > > - put_cpu_var(taskstats_seqnum);
> > > + int seq = this_cpu_inc_return(taskstats_seqnum);
> >
> > Hmmm, wouldn't seq now always be one more than before?
> >
> > I think that "seq = get_cpu_var(taskstats_seqnum)++" first assigns
> > taskstats_seqnum to seq and then increases the value in contrast to
> > this_cpu_inc_return() that returns the already increased value, correct?
>
> Correct. We need to subtract one from that (which will eliminate the minus
> -1 that the inline this_cpu_inc_return creates).
>
But that breaks current behaviour, we should probably initialize all
of the array to -1?
--
Three Cheers,
Balbir
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next prev parent reply other threads:[~2010-12-07 5:58 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-11-30 19:07 [thisops uV3 00/18] Upgrade of this_cpu_ops V3 Christoph Lameter
2010-11-30 19:07 ` [thisops uV3 01/18] percpucounter: Optimize __percpu_counter_add a bit through the use of this_cpu() options Christoph Lameter
2010-11-30 19:07 ` [thisops uV3 02/18] vmstat: Optimize zone counter modifications through the use of this cpu operations Christoph Lameter
2010-11-30 19:07 ` [thisops uV3 03/18] percpu: Generic support for this_cpu_add,sub,dec,inc_return Christoph Lameter
2010-11-30 19:07 ` [thisops uV3 04/18] x86: Support " Christoph Lameter
2010-11-30 19:07 ` [thisops uV3 05/18] x86: Use this_cpu_inc_return for nmi counter Christoph Lameter
2010-11-30 19:07 ` [thisops uV3 06/18] vmstat: Use this_cpu_inc_return for vm statistics Christoph Lameter
2010-11-30 19:07 ` [thisops uV3 07/18] highmem: Use this_cpu_xx_return() operations Christoph Lameter
2010-11-30 19:13 ` Eric Dumazet
2010-11-30 19:19 ` Peter Zijlstra
2010-11-30 19:26 ` Christoph Lameter
2010-11-30 19:29 ` Eric Dumazet
2010-11-30 19:38 ` Peter Zijlstra
2010-11-30 19:53 ` Christoph Lameter
2010-11-30 19:07 ` [thisops uV3 08/18] Taskstats: Use this_cpu_ops Christoph Lameter
2010-12-01 18:06 ` Michael Holzheu
2010-12-01 18:13 ` Christoph Lameter
2010-12-06 14:32 ` Balbir Singh [this message]
2010-12-07 14:39 ` Christoph Lameter
2010-11-30 19:07 ` [thisops uV3 09/18] fs: Use this_cpu_xx operations in buffer.c Christoph Lameter
2010-11-30 19:07 ` [thisops uV3 10/18] x86: Use this_cpu_ops to optimize code Christoph Lameter
2010-11-30 19:07 ` [thisops uV3 11/18] x86: Use this_cpu_ops for current_cpu_data accesses Christoph Lameter
2010-11-30 19:07 ` [thisops uV3 12/18] Core: Replace __get_cpu_var with __this_cpu_read if not used for an address Christoph Lameter
2010-11-30 19:07 ` [thisops uV3 13/18] drivers: " Christoph Lameter
2010-11-30 19:07 ` [thisops uV3 14/18] lguest: Use this_cpu_ops Christoph Lameter
2010-12-06 7:46 ` Rusty Russell
2010-12-06 15:54 ` Christoph Lameter
2010-12-06 16:27 ` Christoph Lameter
2010-11-30 19:07 ` [thisops uV3 15/18] Xen: " Christoph Lameter
2010-11-30 20:53 ` Jeremy Fitzhardinge
2010-11-30 21:03 ` Christoph Lameter
2010-11-30 19:07 ` [thisops uV3 16/18] kprobes: " Christoph Lameter
2010-11-30 19:07 ` [thisops uV3 17/18] Connector: Use this_cpu operations Christoph Lameter
2010-11-30 19:07 ` [thisops uV3 18/18] Fakekey: Simplify speakup_fake_key_pressed through this_cpu_ops Christoph Lameter
2010-11-30 20:05 ` [extra] timers: Use this_cpu_read Christoph Lameter
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