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Subject: Re: [PATCH] si time accounting accounts bh_disable'd time to si
From: Eric Dumazet <eric.dumazet@gmail.com>
To: Venkatesh Pallipadi <venki@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
        Martin Schwidefsky <schwidefsky@de.ibm.com>,
        Ingo Molnar <mingo@elte.hu>, "H. Peter Anvin" <hpa@zytor.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Balbir Singh <balbir@linux.vnet.ibm.com>, linux-kernel@vger.kernel.org,
        Paul Turner <pjt@google.com>
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Date: Mon, 27 Sep 2010 23:16:09 +0200
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Le lundi 27 septembre 2010 à 14:11 -0700, Venkatesh Pallipadi a écrit :
> On Mon, Sep 27, 2010 at 1:53 PM, Eric Dumazet <eric.dumazet@gmail.com> wrote:

> > But softirq handlers sometime call functions that might disable bh
> > again. It would be good to not switch softirq time to system time ;)
> 
> Yes. Good point :-). I should rather have
> +#define in_serving_softirq() (softirq_count() & SOFTIRQ_OFFSET)
> 
> >
> > Shouldnt we reserve a bit (high order bit out of 8) instead ?
> >
> >  * PREEMPT_MASK:    0x000000ff
> >  * SOFTIRQ_MASK:    0x0000ff00
> >  * SERVING_SOFTIRQ: 0x00008000
> >  * HARDIRQ_MASK:    0x03ff0000
> >  *     NMI_MASK:    0x04000000
> 
> Things will be very much similar using higher order bit or lower order
> bit. Somehow I felt using lower order bit was cleaner...
> 

No problem, I now undertand what you wanted to achieve ;)