On Nov 5, 2008, at 4:55 AM, 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.
since procwrite doesn't acquire anything other than the debug lock,
how do you know? the proc could start up again before you notice.
How? If there's a stop message already written to /proc/n/ctl. Once
that is done, the process is guaranteed to be in 2 states and those
states only: continue waiting for the I/O, being actually Stopped.
Both of the don't let the scheduler take it to the runqueue.
the place to catch processes is on syscall entry and/or exit. stop
messages are only checked on syscall entry.
i have a feeling that you want something other than notes for
your problem.
If by the problem you mean stopping a process doing I/O than,
I would gladly accept any solution be it notes or otherwise.
cpu arranges that del works.
Well, it doesn't on Stopped processes.
Thanks,
Roman.
