From: Peter Zijlstra <peterz@infradead.org>
To: Kostya B <bkostya@hotmail.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: __do_softirq and real-time execution context
Date: Mon, 04 Aug 2008 09:41:23 +0200 [thread overview]
Message-ID: <1217835683.11946.3.camel@twins> (raw)
In-Reply-To: <BAY121-W448F461B7F7E5DA621A237B6780@phx.gbl>
On Mon, 2008-08-04 at 07:02 +0000, Kostya B wrote:
> Hello,
>
> Please consider the following:
>
> __do_softirq could be run from several checkpoints in kernel and even can employ userspace process context.
> For example, under heavy network traffic such process could be blocked for a relatively large period until ksoftirqd wakes up and takes control for Rx/Tx.
>
> In the case of regular userspace process the ksoftirqd solves the kernel/user trade-off problem pretty well.
> However, in the case of _real-time_ process, such behavior may yield severe outcomes. Real-time (e.g. NTPL FIFO thread) might require short responses and low latency.
>
> The proposal is that __do_softirq should not run its pending tasks in the context of RT process. Just check has_rt_policy() and immediately wake up ksoftirqd.
Please look at the -rt patches.
prev parent reply other threads:[~2008-08-04 7:41 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <S1754783AbYHDGgc/20080804063632Z+270@vger.kernel.org>
2008-08-04 7:02 ` __do_softirq and real-time execution context Kostya B
2008-08-04 7:41 ` Peter Zijlstra [this message]
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