From: Ingo Molnar <mingo@elte.hu>
To: "David S. Miller" <davem@davemloft.net>
Cc: mgross@linux.intel.com, rostedt@goodmis.org,
linux-kernel@vger.kernel.org, Mark_H_Johnson@raytheon.com
Subject: Re: queue_work from interrupt Real time preemption2.6.11-rc2-RT-V0.7.37-03
Date: Thu, 17 Feb 2005 08:52:12 +0100 [thread overview]
Message-ID: <20050217075212.GA21621@elte.hu> (raw)
In-Reply-To: <20050216081143.50d0a9d6.davem@davemloft.net>
* David S. Miller <davem@davemloft.net> wrote:
> > Maybe the networking
> > stack would break if we allowed the TIMER softirq (thread) to preempt
> > the NET softirq (threads) (and vice versa)?
>
> The major assumption is that softirq's run indivisibly per-cpu.
> Otherwise the per-cpu queues of RX and TX packet work would get
> corrupted.
as long as it stays on a single CPU, could we allow softirq contexts to
preempt each other? I.e. we'd keep the per-CPU assumption (that is fair
and needed for performance anyway), but we'd allow NET_TX to preempt
NET_RX and vice versa. Would this corrupt the rx/tx queues? (i suspect
it would.)
(anyway, by adding an explicit no-preempt section around the 'take
current rx queue private, then process it' on PREEMPT_RT it could be
made safe. I'm wondering whether there are any other deeper assumptions
about atomic separation of softirq contexts.)
Ingo
next prev parent reply other threads:[~2005-02-17 7:52 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-02-14 20:40 queue_work from interrupt Real time preemption2.6.11-rc2-RT-V0.7.37-03 Mark Gross
2005-02-14 21:24 ` Steven Rostedt
2005-02-14 22:29 ` Mark Gross
2005-02-15 10:41 ` Ingo Molnar
2005-02-15 18:06 ` Mark Gross
2005-02-16 5:16 ` Ingo Molnar
2005-02-16 16:11 ` David S. Miller
2005-02-16 17:59 ` George Anzinger
2005-02-16 22:55 ` Mark Gross
2005-02-16 18:02 ` Steven Rostedt
2005-02-17 7:57 ` Ingo Molnar
2005-02-17 15:13 ` Steven Rostedt
2005-02-17 7:52 ` Ingo Molnar [this message]
2005-02-17 14:57 ` Steven Rostedt
2005-02-17 16:14 ` Mark Gross
2005-03-29 8:57 ` Ingo Molnar
2005-03-31 18:41 ` Mark Gross
2005-04-01 5:55 ` Ingo Molnar
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