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From: Nick Piggin <piggin@cyberone.com.au>
To: Tim Hockin <thockin@hockin.org>
Cc: Rusty Russell <rusty@au1.ibm.com>,
	vatsa@in.ibm.com, linux-kernel@vger.kernel.org,
	torvalds@osdl.org, akpm@osdl.org, rml@tech9.net
Subject: Re: CPU Hotplug: Hotplug Script And SIGPWR
Date: Tue, 20 Jan 2004 18:45:37 +1100	[thread overview]
Message-ID: <400CDCA1.5070200@cyberone.com.au> (raw)
In-Reply-To: <20040120073032.GB12638@hockin.org>



Tim Hockin wrote:

>On Tue, Jan 20, 2004 at 06:11:49PM +1100, Nick Piggin wrote:
>
>>I thought hotplug is allowed to fail? Thus you can have a hung system.
>>Or what if the hotplug script itself becomes TASK_UNRUNNABLE? What if the
>>process needs a guaranteed scheduling latency?
>>
>
>I guess a hotplug script MAY fail.  I don't think it's a good idea to make
>your CPU hotplug script fail.  May and Misght are different.  It's up to the
>implementor whether the script can get into a failure condition.
>

Sorry bad wording. The script may fail to be executed.

>
>The hotplug script can only become unrunnable if you yank out all the CPUs
>on the system.  I'd assume it would have an affinity of 0xffffffff.
>

OK I guess thats not such a valid concern

>
>What if <which> process needs guaranteed scheduling latency?  Do we really
>_guarantee_ scheduling latency *anywhere*?
>
>

We do guarantee that a realtime task won't be blocked waiting for
a hotplug script to fault in and start it up again (which may not
happen). Not sure how important this issue is.



  reply	other threads:[~2004-01-20  7:45 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20040116174446.A2820@in.ibm.com>
2004-01-20  5:44 ` CPU Hotplug: Hotplug Script And SIGPWR Rusty Russell
2004-01-20  6:33   ` Tim Hockin
2004-01-20  6:43     ` Nick Piggin
2004-01-20  6:52       ` Tim Hockin
2004-01-20  7:11         ` Nick Piggin
2004-01-20  7:30           ` Tim Hockin
2004-01-20  7:45             ` Nick Piggin [this message]
2004-01-20  7:54               ` Tim Hockin
2004-01-20  8:14                 ` Nick Piggin
2004-01-20  8:29                   ` Tim Hockin
2004-01-20  8:37                     ` Nick Piggin
2004-01-20  8:43                       ` Tim Hockin
2004-01-21  4:06                         ` Srivatsa Vaddagiri
2004-01-21  4:14                           ` Nick Piggin
2004-01-21  5:09                             ` Srivatsa Vaddagiri
2004-01-21  7:08                               ` Tim Hockin
2004-01-21 15:07                                 ` Matthias Urlichs
2004-01-22  5:29                                 ` Rusty Russell
2004-01-21  7:09                             ` Tim Hockin
2004-01-21  7:31                               ` Nick Piggin
2004-01-21  7:42                                 ` Tim Hockin
2004-01-21  8:11                             ` Rusty Russell
2004-01-21  5:07                           ` Rusty Russell
2004-01-20  8:41                   ` Stefan Smietanowski
2004-01-20  8:49                     ` Nick Piggin
2004-01-20  9:12                       ` Tim Hockin
2004-01-21  0:00                 ` Rusty Russell
2004-01-20 23:51         ` Rusty Russell
2004-01-20  7:45     ` Rusty Russell
2004-01-20  8:37       ` Tim Hockin
2004-01-20  9:29         ` Srivatsa Vaddagiri
2004-01-21  0:12         ` Rusty Russell
     [not found] <fa.f37o48p.1io5q5@ifi.uio.no>
     [not found] ` <fa.frjqvfo.170g8hq@ifi.uio.no>
2004-01-20 17:49   ` Andy Lutomirski
2004-01-21  4:33     ` Rusty Russell

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