From: Oleg Nesterov <oleg@redhat.com>
To: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: Ivo Sieben <meltedpianoman@gmail.com>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
linux-kernel@vger.kernel.org, Andi Kleen <andi@firstfloor.org>,
Jiri Slaby <jslaby@suse.cz>, Alan Cox <alan@lxorguk.ukuu.org.uk>,
linux-serial@vger.kernel.org, Alan Cox <alan@linux.intel.com>,
Greg KH <gregkh@linuxfoundation.org>
Subject: Re: [PATCH] tty: Only wakeup the line discipline idle queue when queue is active
Date: Fri, 18 Jan 2013 16:45:04 +0100 [thread overview]
Message-ID: <20130118154504.GA28072@redhat.com> (raw)
In-Reply-To: <50F7D8C2.1030506@linux.vnet.ibm.com>
On 01/17, Preeti U Murthy wrote:
>
> On 01/16/2013 05:32 PM, Ivo Sieben wrote:
> >
> > I don't have a problem that there is a context switch to the high
> > priority process: it has a higher priority, so it probably is more
> > important.
> > My problem is that even when the waitqueue is empty, the high priority
> > thread has a risk to block on the spinlock needlessly (causing context
> > switches to low priority task and back to the high priority task)
> >
> Fair enough Ivo.I think you should go ahead with merging the
> waitqueue_active()
> wake_up()
> logic into the wake_up() variants.
This is not easy. We can't simply change wake_up*() helpers or modify
__wake_up().
I can't understand why do you dislike Ivo's simple patch. There are
a lot of "if (waitqueue_active) wake_up" examples. Even if we add the
new helpers (personally I don't think this makes sense) , we can do
this later. Why should we delay this fix?
Oleg.
next prev parent reply other threads:[~2013-01-18 15:45 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-12-18 14:48 [PATCH] tty: Only wakeup the line discipline idle queue when queue is active Ivo Sieben
2013-01-02 9:29 ` Jiri Slaby
2013-01-02 11:43 ` Alan Cox
2013-01-02 15:21 ` Ivo Sieben
2013-01-02 19:06 ` Jiri Slaby
2013-01-03 9:49 ` Ivo Sieben
2013-01-03 18:36 ` Oleg Nesterov
2013-01-15 9:16 ` Ivo Sieben
2013-01-15 18:03 ` Oleg Nesterov
2013-01-16 8:13 ` Preeti U Murthy
2013-01-16 9:16 ` Ivo Sieben
2013-01-16 10:41 ` Preeti U Murthy
2013-01-16 12:02 ` Ivo Sieben
2013-01-17 10:56 ` Preeti U Murthy
2013-01-18 15:45 ` Oleg Nesterov [this message]
2013-01-21 2:56 ` Preeti U Murthy
2013-01-21 7:20 ` Ivo Sieben
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