From mboxrd@z Thu Jan  1 00:00:00 1970
Date: Tue,  4 Nov 2008 20:22:04 -0800
From: Roman Shaposhnik <rvs@sun.com>
In-reply-to: <4eb80fc92bc1672ed138579aba434cf0@quanstro.net>
To: Fans of the OS Plan 9 from Bell Labs <9fans@9fans.net>
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Subject: Re: [9fans] Quick question on stopping a process that waits for IO
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On Nov 4, 2008, at 8:01 PM, erik quanstrom wrote:

>> I'm asking is -- "dear kernel, please don't advance this process even
>> if you otherwise can". All I need is a frozen state so that I can
>
> not so easy on a multiprocessor.  (unless you turn all but one
> processor off.)

Hm. May be its getting late, but I can't quite see why that would
be the case (or may be I didn't quite communicate the intent
in my plea to the kernel ;-))

The target process is *already* waiting for the IO stuck inside the
kernel. It is not on a runqueue, not it is considered to be places
there.
All of the user-level data structures are frozen and
not changing. All I'm asking is that if, and only if, the process
gets attention from the scheduler (for whatever reason) it doesn't
get placed on a runque.

I don't quite see how MP would matter in this case.

Thanks,
Roman.