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From: "Hawkes Steve-FSH016" <Steve.Hawkes@motorola.com>
To: "Andrew Morton" <akpm@linux-foundation.org>
Cc: <davem@davemloft.net>, <joe@perches.com>,
	<linux-kernel@vger.kernel.org>, <netdev@vger.kernel.org>
Subject: RE: printk_ratelimit and net_ratelimit conflict and tunable behavior
Date: Thu, 28 Feb 2008 10:19:02 -0600	[thread overview]
Message-ID: <7BFDACCD6948EF4D8FE8F4888A91596A01637208@tx14exm60.ds.mot.com> (raw)
In-Reply-To: <20080225154521.e119cbb6.akpm@linux-foundation.org>

Andrew Morton wrote:

> This patch causes a large and nasty reject.
> Probably because you patched 2.6.24.  We're developing 2.6.25 now, and
> the difference between the two is very large inded.  Please raise
patches
> against Linus's latest tree?

Will do. I'm learning the process. I assume Linus's latest tree is the
one
listed as the latest prepatch for the stable Linux kernel tree.

Andrew Morton wrote:

> > struct printk_ratelimit_state {
> > +	unsigned long toks;
> > +	unsigned long last_jiffies;
> > +	int missed;
> > +	int limit_jiffies;
> > +	int limit_burst;
> > +	char const *facility;
> > +};
> 
> I find that the best-value comments one can add to kernel code are to
the
> members of structures.  If the reader understands what all the fields
do, the
> code becomes simple to follow.

Agreed. Although the current kernel source doesn't document these
attributes, there's no reason I couldn't add documentation for them.

Andrew Morton wrote:

> >  int net_ratelimit(void)
> >  {
> > -	return __printk_ratelimit(net_msg_cost, net_msg_burst);
> > +	static struct printk_ratelimit_state limit_state = {
> > +		.toks          = 10 * 5 * HZ,
> > +		.last_jiffies  = 0,
> > +		.missed        = 0,
> > +		.limit_jiffies = 5 * HZ,
> > +		.limit_burst   = 10,
> > +		.facility      = "net"
> > +	};
> > +
> > +	return __printk_ratelimit(net_msg_cost, net_msg_burst,
&limit_state);
> 
> I don't get it.  There's one instance of limit_state, kernel-wide, and
> __printk_ratelimit() modifies it.  What prevents one CPU's activities
from
> interfering with a second CPU's activities?

The state is protected by the spinlock in __printk_ratelimit, like it is
in
the current kernel. Am I missing something?

  reply	other threads:[~2008-02-28 16:19 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-02-25 20:36 Steven Hawkes
2008-02-25 23:45 ` Andrew Morton
2008-02-28 16:19   ` Hawkes Steve-FSH016 [this message]
2008-02-28 18:39     ` Andrew Morton
  -- strict thread matches above, loose matches on Subject: below --
2008-02-28 16:10 Steven Hawkes
2008-02-19 21:30 Hawkes Steve-FSH016
2008-02-21  6:32 ` David Miller
2008-02-21  7:00   ` Joe Perches
2008-02-25 15:47     ` Hawkes Steve-FSH016
2008-02-25 20:02       ` David Miller
2008-02-25 20:13       ` Joe Perches
     [not found]         ` <7BFDACCD6948EF4D8FE8F4888A91596A016371FE@tx14exm60.ds.mot.com>
2008-02-26  0:04           ` Joe Perches

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