From: Greg KH <greg@kroah.com>
To: Joe Perches <joe@perches.com>
Cc: Alan Stern <stern@rowland.harvard.edu>,
Kay Sievers <kay@vrfy.org>,
Kernel development list <linux-kernel@vger.kernel.org>,
Jason Baron <jbaron@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: Excessive latency for dev_dbg?
Date: Wed, 23 May 2012 19:12:08 -0700 [thread overview]
Message-ID: <20120524021208.GA12557@kroah.com> (raw)
In-Reply-To: <1337805903.1747.0.camel@joe2Laptop>
On Wed, May 23, 2012 at 01:45:03PM -0700, Joe Perches wrote:
> cc'ing Kay.
>
> On Wed, 2012-05-23 at 16:37 -0400, Alan Stern wrote:
> > I just tried doing some testing of 3.4. Sequences of literally
> > adjacent dev_dbg() calls -- with local interrupts disabled -- show up
> > in the log buffer spaced at time intervals between 1 and 4
> > milliseconds!
> >
> > This is with CONFIG_DYNAMIC_DEBUG not enabled, and CONFIG_PRINTK_TIME,
> > CONFIG_PREEMPT, CONFIG_HIGH_RES_TIMERS, and CONFIG_HPET_TIMER all set
> > to y.
> >
> > What's going on here? Did printk suddenly slow down a lot? Or has the
> > timer code gone crazy?
Joe, why ask Kay? He didn't touch this code until 3.5-rc1, and Alan is
testing 3.4.
confused,
greg k-h
next prev parent reply other threads:[~2012-05-24 2:12 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-05-23 20:37 Alan Stern
2012-05-23 20:45 ` Joe Perches
2012-05-24 2:12 ` Greg KH [this message]
2012-05-24 2:13 ` Joe Perches
2012-05-24 17:57 ` Alan Stern
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