RE: race condition?

Moshe,
Agreed.   How? How does/should the deputy know that the remote has just
sent a syscall, so don't do anything until it has processed the syscall
and sent the response? 

Send reqs and acks before any data exchange? More extensive use of
omp_mig_handshake?

Tab, what are your thoughts?

Matt




>>> "Moshe Bar" <moshe-ay74M1d3r6RWk0Htik3J/[email protected]> 05/08/06 2:59 PM >>>
I think the best approach is to not let it migrate home (or elsewhere)
until
the outstanding syscall(s) have been answered. 

 Moshe

-----Original Message-----
From: openmosix-devel-admin-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org
[mailto:openmosix-devel-admin-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org] On Behalf Of Matt
Dew
Sent: Monday, May 08, 2006 11:00 AM
To: openMosix-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org
Cc: [email protected]
Subject: [Openmosix-devel] race condition?

(I'm having trouble sending to the list and have been asked to resend so
I
apologize if you've received this message several times.)

Hi Tab, et al,
 What are the thoughts on the condition where the remote node sends a
syscall back to the home node and then receives a migrate home command
before the syscall response?   Is this the same problem (out of
sync-ness) that is causing the received -32 of 8 errors?

What is the best way to fix this?  
 1) Put in some ack/nack commands to ensure both remote and deputy are
in
the same place?
 2) Open two ports. One for migration stuff and another for syscalls?
 3) Modify the functions to handle these cases?
 4) Add a counter field to the structs for bookkeeping; so both remote
and
deputy know which response goes with which command and then merge the
calling functions?
 5) I'm simply not seeing the logic that is already supposed to handle
these?

I'm hoping it's 5, but if it's not;
3 seems like a bad idea and will probably not scale well.  2 might scale
the
best and be most robust??

The simple attached program shows it reliably.  It'll crash when trying
to
migate back home.

Matt 




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