Subject: [Tsvwg] SIGIO and SCTP?

From: Brad Penoff <[email-masked]>
Date: Sun, 18 Sep 2005 00:19:41 -0700 (PDT)

Greetings,

I was wondering, is the behavior of a SIGIO signal defined for an SCTP 
socket (in either coding style)?  If so, could you please point me to 
where I could read more about it?  If not, is there any intension to ever
define the behavior?

Thanks,
brad

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From: Michael Tuexen <[email-masked]>
Date: Mon, 19 Sep 2005 20:29:47 +0200

Hi Brad,

Unix Network Programming Vol 1, Third edition, states that SIGIO is 
nearly useless for TCP, because
there are so many events. I guess SCTP would be similar...

Do you know about an implementation using SIGIO which should also run 
on SCTP?

Best regards
Michael

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From: Randall Stewart <[email-masked]>
Date: Mon, 19 Sep 2005 16:00:19 -0400

> there are so many events. I guess SCTP would be similar...
Actually.. if you consider the notifications as yet
other types of events... I would think that SCTP
and SIGIO would even be more useless :-D

R

> 
> Do you know about an implementation using SIGIO which should also run on 
> SCTP?
> 
> Best regards
> Michael
> 

-- 
Randall Stewart
803-345-0369 <or> 815-342-5222(cell)

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From: "Brian F. G. Bidulock" <[email-masked]>
Date: Mon, 19 Sep 2005 16:02:01 -0600

Michael,

Actualyl it is quite useful, particularly with SIGURG and with
POSIX extended signals returning the sigevent structure.  It is
as good as poll(2).  It is indeed hard to support the one without
the other.

--brian

-- 
Brian F. G. Bidulock    ¦ The reasonable man adapts himself to the ¦
[email-masked]    ¦ world; the unreasonable one persists in  ¦
http://www.openss7.org/ ¦ trying  to adapt the  world  to himself. ¦
                        ¦ Therefore  all  progress  depends on the ¦
                        ¦ unreasonable man. -- George Bernard Shaw ¦

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From: Brad Penoff <[email-masked]>
Date: Mon, 19 Sep 2005 14:00:02 -0700 (PDT)

hey Michael,

I had reviewed that part of UNPv1e3 and it was what originally sparked my 
interest.  As it does say that using SIGIO for TCP may be difficult to 
distinguish why it was thrown, it seems to suggest it could be more useful 
for UDP.  In our work, we have an implementation of a parallel message 
passing library that runs atop a one-to-many socket (the "UDP style", in 
the old terminology); this made us wonder about SIGIO and SCTP.

Our work is discussed off this page:
http://www.cs.ubc.ca/labs/dsg/mpi-sctp/
We plan on releasing the middleware code soon (Supercomputing 05) but we 
know that it will not support one-sided MPI operations in our first 
release.  In order to properly implement one-sided operations, some sort 
of asynchronous agent will be required.  We're simply reviewing what 
options exist (threads, events, signals, etc), so I wanted to query about 
SIGIO and SCTP.

You had asked about SIGIO-based code that we'd like to run over SCTP...
As far as others in the MPI community that make use of SIGIO over TCP, 
Turner's work on MP_Lite comes to mind:
http://www.scl.ameslab.gov/Projects/MP_Lite/
...as well as Matsuda's work on O2G:
http://www.gridmpi.org/publications/cluster04-matsuda.pdf

I don't know exactly how/if these solved the problem of having an 
excessive number of conditions for which SIGIO is thrown in TCP, but these 
strategies are what we'd like to explore for SCTP using the UDP style; 
this is why I was curious if defining SIGIO's behavior for SCTP was done 
yet, or if it ever will be...

Thanks,
brad

On Mon, 19 Sep 2005, Michael Tuexen wrote:

> Hi Brad,
>
> Unix Network Programming Vol 1, Third edition, states that SIGIO is nearly 
> useless for TCP, because

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From: Michael Tuexen <[email-masked]>
Date: Tue, 20 Sep 2005 10:07:32 +0200

Hi Brad,

see my comments in-line.

Best regards
Michael

On Sep 19, 2005, at 23:00 Uhr, Brad Penoff wrote:

> hey Michael,
>
> I had reviewed that part of UNPv1e3 and it was what originally sparked 
> my interest.  As it does say that using SIGIO for TCP may be difficult 
> to distinguish why it was thrown, it seems to suggest it could be more 
> useful for UDP.  In our work, we have an implementation of a parallel 
> message passing library that runs atop a one-to-many socket (the "UDP 
> style", in the old terminology); this made us wonder about SIGIO and 
> SCTP.
>
> We plan on releasing the middleware code soon (Supercomputing 05) but 
> we know that it will not support one-sided MPI operations in our first 
> release.  In order to properly implement one-sided operations, some 
> sort of asynchronous agent will be required.  We're simply reviewing 
> what options exist (threads, events, signals, etc), so I wanted to 
> query about SIGIO and SCTP.
>
> excessive number of conditions for which SIGIO is thrown in TCP, but 
> these strategies are what we'd like to explore for SCTP using the UDP 
> style; this is why I was curious if defining SIGIO's behavior for SCTP 
> was done yet, or if it ever will be...
Handling the large number of conditions is the problem here. I think 
nothing is specified yet, if you figure out how this
can be done, I'm interested in.
>>> I was wondering, is the behavior of a SIGIO signal defined for an 
>>> SCTP socket (in either coding style)?  If so, could you please point 
>>> me to where I could read more about it?  If not, is there any 
>>> intension to ever
>>> define the behavior?
>>> Thanks,
>>> brad

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From: Kacheong Poon <[email-masked]>
Date: Tue, 20 Sep 2005 23:30:14 +0800

> where I could read more about it?  If not, is there any intension to ever

I don't know if it is appropriate to define SIGIO (or SIGPOLL)
behavior in the socket draft.  It seems more appropriate for
the OS signal handling manual page.

Anyway, if you use Solaris, you can enable SIGPOLL and should
get the signal whenever the socket (1-1 or 1-N style) has a
"selectable" event pending.

-- 

						K. Poon.
						[email-masked]