From: "Chris Friesen" <cfriesen@nortel.com>
To: Andi Kleen <andi@firstfloor.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>,
netdev@vger.kernel.org, Ingo Molnar <mingo@elte.hu>,
Steven Rostedt <rostedt@goodmis.org>,
linuxppc-dev@ozlabs.org, paulus@samba.org,
Thomas Gleixner <tglx@linutronix.de>,
David Miller <davem@davemloft.net>
Subject: Re: question about softirqs
Date: Wed, 13 May 2009 09:05:01 -0600 [thread overview]
Message-ID: <4A0AE19D.9040509@nortel.com> (raw)
In-Reply-To: <87my9hkrmw.fsf@basil.nowhere.org>
Andi Kleen wrote:
> Thomas Gleixner <tglx@linutronix.de> writes:
>>Err, no. Chris is completely correct:
>>
>> if (!in_interrupt())
>> wakeup_softirqd();
>
> Yes you have to wake it up just in case, but it doesn't normally
> process the data because a normal softirq comes in faster. It's
> just a safety policy.
What about the scenario I raised earlier, where we have incoming network
packets, no hardware interrupts coming in other than the timer tick, and
a high-priority userspace app is spinning on recvmsg() with MSG_DONTWAIT
set?
As far as I can tell, in this scenario softirqs may not get processed on
return from a syscall (contradicting the documentation). In the worst
case, they may not get processed until the next timer tick.
Chris
next prev parent reply other threads:[~2009-05-13 15:31 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-05-08 22:51 question about softirqs Chris Friesen
2009-05-08 23:05 ` David Miller
2009-05-08 23:34 ` Paul Mackerras
2009-05-08 23:53 ` David Miller
2009-05-09 2:52 ` Benjamin Herrenschmidt
2009-05-09 3:31 ` Paul Mackerras
2009-05-09 6:48 ` David Miller
2009-05-11 18:25 ` Chris Friesen
2009-05-11 23:24 ` David Miller
2009-05-12 0:43 ` Chris Friesen
2009-05-12 8:12 ` Ingo Molnar
2009-05-12 9:12 ` Peter Zijlstra
2009-05-12 9:23 ` Ingo Molnar
2009-05-12 9:32 ` Peter Zijlstra
2009-05-12 12:20 ` Steven Rostedt
2009-05-13 4:45 ` David Miller
2009-05-13 4:44 ` David Miller
2009-05-13 5:15 ` Paul Mackerras
2009-05-13 5:28 ` David Miller
2009-05-13 5:55 ` Evgeniy Polyakov
2009-05-12 15:18 ` Chris Friesen
2009-05-13 8:34 ` Andi Kleen
2009-05-13 13:23 ` Chris Friesen
2009-05-13 14:15 ` Andi Kleen
2009-05-13 14:17 ` Thomas Gleixner
2009-05-13 14:24 ` Andi Kleen
2009-05-13 14:54 ` Eric Dumazet
2009-05-13 15:02 ` Andi Kleen
2009-05-13 15:05 ` Chris Friesen [this message]
2009-05-13 15:54 ` Thomas Gleixner
2009-05-13 16:10 ` Chris Friesen
2009-05-13 17:01 ` Andi Kleen
2009-05-13 19:04 ` Chris Friesen
2009-05-13 19:13 ` Andi Kleen
2009-05-13 19:44 ` Chris Friesen
2009-05-13 19:53 ` Andi Kleen
2009-05-13 20:55 ` Thomas Gleixner
2009-05-11 23:34 ` Paul Mackerras
2009-05-09 0:28 ` Chris Friesen
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