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Re: [patch] CFS scheduler, -v19

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To: Ingo Molnar <mingo@...>
Cc: Markus <lists4me@...>, Linux Kernel Mailing List <linux-kernel@...>, Andrew Morton <akpm@...>, Mike Galbraith <efault@...>, Arjan van de Ven <arjan@...>, Thomas Gleixner <tglx@...>, Dmitry Adamushko <dmitry.adamushko@...>, Srivatsa Vaddagiri <vatsa@...>, Alan Cox <alan@...>
Date: Tuesday, July 17, 2007 - 4:37 pm

On Tue, 17 Jul 2007, Ingo Molnar wrote:

Well, it's preceded by a poll() that says that it has a POLLHUP event, so 
that socket would seem to have simply been closed from the other end. 
There's also a huge amount of select() calls showing the same thing 
(except since it's just the input side, you cannot tell that it's 
POLLHUP).

Don't ask me *why*, though. It's preceded by

	..
	11902 1184699848.615201 read(3, 0x7fffb5b9c8b0, 32) = -1 EAGAIN (Resource temporarily unavailable) <0.000009>
	11902 1184699848.615252 poll([{fd=3, events=POLLIN, revents=POLLIN}], 1, -1) = 1 <0.009307>
	11902 1184699848.624614 read(3, "\1 \303!\0\0\0\0\4\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0b\340T\0\0\0\0\0", 32) = 32 <0.000011>

.. got data ..

	11902 1184699848.624710 ioctl(3, FIONREAD, [0]) = 0 <0.000009>
	11902 1184699848.624762 ioctl(3, FIONREAD, [0]) = 0 <0.000048>

.. ok, nothing more..

	11902 1184699848.624866 select(10, [3 4 5 7 9], [], [], NULL) = 1 (in [3]) <16.495008>
	11902 1184699865.119950 ioctl(3, FIONREAD, [0]) = 0 <0.000006>

16+ seconds pass, now it's marked as readable, but returns zero bytes of 
data: the other end closed it.

Tons of unnecessary and stupid sequences of:

	11902 1184699865.119988 select(10, [3 4 5 7 9], [], [], NULL) = 1 (in [3]) <0.000007>
	11902 1184699865.120031 ioctl(3, FIONREAD, [0]) = 0 <0.000005>
	..

and then finally:

	...
	11902 1184699865.141809 poll([{fd=3, events=POLLIN, revents=POLLIN|POLLHUP}], 1, 0) = 1 <0.000005>
	11902 1184699865.141838 ioctl(3, FIONREAD, [0]) = 0 <0.000005>
	11902 1184699865.141939 read(3, "", 32) = 0 <0.000007>

ie now konqueror noticed that it was *really* closed, and read the EOF.

But why does that happen? And why would the scheduler have *anything* to 
do with this? No idea. Maybe timing. Maybe the time.c changes. Dunno.

		Linus
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Messages in current thread:
[patch] CFS scheduler, -v19, Ingo Molnar, (Fri Jul 6, 1:33 pm)
Re: [patch] CFS scheduler, -v19, Ed Tomlinson, (Sat Jul 14, 1:19 pm)
Re: [patch] CFS scheduler, -v19, Ingo Molnar, (Mon Jul 16, 5:17 am)
Re: [patch] CFS scheduler, -v19, Ed Tomlinson, (Mon Jul 16, 7:10 am)
Re: [patch] CFS scheduler, -v19, Mike Galbraith, (Sun Jul 15, 1:25 am)
Re: [patch] CFS scheduler, -v19, Ingo Molnar, (Mon Jul 16, 4:00 am)
Re: [patch] CFS scheduler, -v19, Markus, (Sun Jul 15, 8:53 am)
Re: [patch] CFS scheduler, -v19, Mike Galbraith, (Sun Jul 15, 3:46 pm)
Re: [patch] CFS scheduler, -v19, Markus, (Sun Jul 15, 5:11 pm)
Re: [patch] CFS scheduler, -v19, Mike Galbraith, (Mon Jul 16, 2:42 am)
Re: [patch] CFS scheduler, -v19, Markus, (Sat Jul 14, 7:34 am)
Re: [patch] CFS scheduler, -v19, Markus, (Sat Jul 14, 11:11 am)
Re: [patch] CFS scheduler, -v19, Ingo Molnar, (Mon Jul 16, 5:41 am)
Re: [patch] CFS scheduler, -v19, Markus, (Mon Jul 16, 1:59 pm)
Re: [patch] CFS scheduler, -v19, Ingo Molnar, (Tue Jul 17, 3:37 am)
Re: [patch] CFS scheduler, -v19, Markus, (Tue Jul 17, 9:06 am)
Re: [patch] CFS scheduler, -v19, Ingo Molnar, (Tue Jul 17, 1:06 pm)
Re: [patch] CFS scheduler, -v19, Markus, (Tue Jul 17, 3:42 pm)
Re: [patch] CFS scheduler, -v19, Ingo Molnar, (Tue Jul 17, 4:09 pm)
Re: [patch] CFS scheduler, -v19, Linus Torvalds, (Tue Jul 17, 4:37 pm)
Re: [patch] CFS scheduler, -v19, Ingo Molnar, (Tue Jul 17, 4:43 pm)
Re: [patch] CFS scheduler, -v19, Markus, (Tue Oct 16, 8:02 pm)
Re: [patch] CFS scheduler, -v19, Markus, (Thu Aug 9, 1:34 pm)
Re: [patch] CFS scheduler, -v19, Ingo Molnar, (Fri Aug 10, 3:46 am)
Re: [patch] CFS scheduler, -v19, Markus, (Tue Aug 14, 1:15 pm)
Re: [patch] CFS scheduler, -v19, Markus, (Fri Jul 20, 6:26 pm)
Re: [patch] CFS scheduler, -v19, Markus, (Tue Jul 17, 6:03 pm)
Re: [patch] CFS scheduler, -v19, Ingo Molnar, (Tue Jul 17, 1:13 pm)
Re: [patch] CFS scheduler, -v19, Mike Galbraith, (Tue Jul 10, 4:08 am)
Re: [patch] CFS scheduler, -v19, Bill Davidsen, (Wed Jul 11, 1:26 pm)
Re: [patch] CFS scheduler, -v19, Ingo Molnar, (Wed Jul 11, 4:55 pm)
Re: [patch] CFS scheduler, -v19, Bill Davidsen, (Fri Jul 13, 5:19 pm)
Re: [patch] CFS scheduler, -v19, Chuck Ebbert, (Mon Jul 16, 5:34 pm)
Re: [patch] CFS scheduler, -v19, Ingo Molnar, (Mon Jul 16, 5:55 pm)
Re: [patch] CFS scheduler, -v19, Ian Kent, (Tue Jul 17, 1:01 am)
Re: [patch] CFS scheduler, -v19, Ingo Molnar, (Tue Jul 17, 3:45 am)
Re: [patch] CFS scheduler, -v19, Linus Torvalds, (Wed Jul 18, 12:03 pm)
Re: [patch] CFS scheduler, -v19, Ingo Molnar, (Thu Jul 19, 4:16 am)
Re: [patch] CFS scheduler, -v19, Bill Davidsen, (Wed Jul 18, 5:37 pm)
Re: [patch] CFS scheduler, -v19, Ingo Molnar, (Thu Jul 19, 10:32 am)
Re: [patch] CFS scheduler, -v19, Bill Davidsen, (Thu Jul 19, 10:32 pm)
Re: [patch] CFS scheduler, -v19, Bill Davidsen, (Thu Jul 19, 1:06 pm)
Re: [patch] CFS scheduler, -v19, Bill Davidsen, (Thu Jul 19, 1:26 pm)
Re: [patch] CFS scheduler, -v19, Ingo Molnar, (Thu Jul 19, 1:42 pm)
Re: [patch] CFS scheduler, -v19, Ingo Molnar, (Thu Jul 19, 1:17 pm)
Re: [patch] CFS scheduler, -v19, Ingo Molnar, (Thu Jul 19, 1:10 pm)
Re: [patch] CFS scheduler, -v19, Ingo Molnar, (Thu Jul 19, 4:53 am)
Re: [patch] CFS scheduler, -v19, Ian Kent, (Wed Jul 18, 1:31 pm)
RE: [patch] CFS scheduler, -v19, David Schwartz, (Tue Jul 17, 5:16 pm)
RE: [patch] CFS scheduler, -v19, Ian Kent, (Wed Jul 18, 1:59 am)
Re: [patch] CFS scheduler, -v19, Ingo Molnar, (Wed Jul 18, 3:54 am)
Re: [patch] CFS scheduler, -v19, Linus Torvalds, (Wed Jul 18, 1:23 pm)
Re: [patch] CFS scheduler, -v19, Bill Davidsen, (Wed Jul 18, 9:50 am)
Re: [patch] CFS scheduler, -v19, Chuck Ebbert, (Tue Jul 17, 12:30 pm)
Re: [patch] CFS scheduler, -v19, Ian Kent, (Tue Jul 17, 7:17 am)
Re: [patch] CFS scheduler, -v19, Ingo Molnar, (Tue Jul 17, 1:16 pm)
Re: [patch] CFS scheduler, -v19, Bill Davidsen, (Tue Jul 17, 9:24 pm)
Re: [patch] CFS scheduler, -v19, Ian Kent, (Wed Jul 18, 2:19 am)
Re: [patch] CFS scheduler, -v19, Bill Davidsen, (Tue Jul 17, 12:22 am)
Re: [patch] CFS scheduler, -v19, Bill Davidsen, (Thu Jul 12, 8:41 am)
Re: [patch] CFS scheduler, -v19, Willy Tarreau, (Sun Jul 8, 1:46 pm)
Re: [patch] CFS scheduler, -v19, Ingo Molnar, (Mon Jul 9, 6:39 pm)
Re: [patch] CFS scheduler, -v19, Willy Tarreau, (Tue Jul 17, 5:44 pm)
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