[mpich-discuss] discuss Digest, Vol 8, Issue 39
Antonio J. Peña
apenya at mcs.anl.gov
Mon Jun 24 16:22:48 CDT 2013
Hi Jeff,
Please correct me where I'm wrong: if only one thread calls MPI_Barrier, that
one will get locked while others will go ahead. On the other hand, if every
thread calls MPI_Barrier, all will get locked in that call until the barrier
completes. That doesn't mean this will be a replacement for thread-wise
synchronization mechanisms, but will be effective for all of them waiting for
the barrier.
Antonio
On Monday, June 24, 2013 04:14:20 PM Jeff Hammond wrote:
> MPI_Barrier will not sync threads. If N threads call MPI_Barrier, you will
> get at best the same result as if you call MPI_Barrier N times from the
> main thread.
>
> If you want to sync threads, you need to sync them with the appropriate
> thread API. OpenMP and Pthreads both have barrier calls. If you want a
> fast Pthread barrier, you should not use pthread_barrier though. The
> Internet has details.
>
> Jeff
>
> ----- Original Message -----
> From: "Antonio J. Peña" <apenya at mcs.anl.gov>
> To: discuss at mpich.org
> Sent: Monday, June 24, 2013 3:49:08 PM
> Subject: Re: [mpich-discuss] discuss Digest, Vol 8, Issue 39
>
>
>
>
>
>
> Sufeng,
>
>
>
> I'd say you're OK syncing your threads by all of them calling MPI_Barrier,
> as it's a thread-safe function.
>
>
>
> Antonio
>
>
>
>
>
> On Monday, June 24, 2013 11:41:44 AM Sufeng Niu wrote:
>
>
> Hi, Antonio
>
>
>
> Thanks a lot! Now I make sense. Let's say if I am running MPI and
> multithreads program. If I called MPI_Barrier in each threads
>
>
> what gonna happen? Will threads be synced by MPI_Barrier? or I should use
> thread level sync?
>
>
>
> Thank you!
>
>
> Sufeng
>
>
>
>
>
>
> On Sun, Jun 23, 2013 at 6:54 PM, < discuss-request at mpich.org > wrote:
>
>
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> Today's Topics:
>
> 1. Re: Error with MPI_Spawn (Jeff Hammond)
> 2. Re: discuss Digest, Vol 8, Issue 37 (Antonio J. Pe?a)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Sun, 23 Jun 2013 17:03:09 -0500
> From: Jeff Hammond < jeff.science at gmail.com >
> To: " discuss at mpich.org " < discuss at mpich.org >
> Subject: Re: [mpich-discuss] Error with MPI_Spawn
> Message-ID: <-1578386667793986954 at unknownmsgid>
> Content-Type: text/plain; charset=ISO-8859-1
>
> This is the wrong way to use PETSc and to parallelize a code with a
> parallel library in general.
>
> Write the PETSc user list and they will explain to you how to
> parallelize your code properly with PETSc.
>
> Jeff
>
> Sent from my iPhone
>
> On Jun 23, 2013, at 4:59 PM, Nitel Muhtaroglu < muhtaroglu.n at gmail.com >
wrote:
> > Hello,
> >
> > I am trying to integrate PETSc library to a serial program. The idea is
> > that the serial program creates a linear equation system and then calls
> > PETSc solver by MPI_Spawn and then solves this system in parallel. But
> > when I execute MPI_Spawn the following error message occurs and the
> > solver is not called. I couldn't find a solution to this error. Does
> > anyone have an idea about it?
> >
> > Kind Regards,
>
> ------------------------------
>
> Message: 2
> Date: Sun, 23 Jun 2013 18:54:38 -0500
> From: Antonio J. Pe?a < apenya at mcs.anl.gov >
> To: discuss at mpich.org
> Subject: Re: [mpich-discuss] discuss Digest, Vol 8, Issue 37
> Message-ID: <8872211.IGCl89YM8r at localhost.localdomain>
> Content-Type: text/plain; charset="iso-8859-1"
>
>
> Sufeng,
>
> The correct way is to use the MPI_Init_thread function with
> MPI_THREAD_MULTIPLE. This will tell the MPI implementation to be thread
> safe. It supports OpenMP and Posix Threads (OpenMP primitives in most
> systems are likely to be implemented on top of PThreads).
>
> Antonio
>
>
> On Sunday, June 23, 2013 11:13:31 AM Sufeng Niu wrote:
>
>
> Hi, Antonio
>
>
> Thanks a lot for your reply, I just figure out that is the firewall issue.
> after I set the firewall. it works now. Thanks again.
>
>
> But I still got a few questions on MPI and multithreads mixed programming.
> Currently, I try to run each process on each server, and each process
> using thread pool to run multiple threads (pthread lib). I am not sure
> whether it is the correct way or not. I wrote it as:
>
>
> MPI_Init()
> ....
> ...
> /* create thread pool and initial */
> ......
> /* fetch job into thread pool */
> ......
>
>
> MPI_Finalize();
>
>
> When I check the book and notes, I found people use
>
>
> MPI_Init_thread() with MPI_THREAD_MULTIPLE
>
>
> but the some docs said it supported OpenMP, is that possible to use it
> with pthread library?
> I am new guy to this hybrid programming. I am not sure which is the proper
> way to do it. Any suggestions are appreciate. Thank you!
>
>
> Sufeng
>
>
>
>
> On Sat, Jun 22, 2013 at 12:12 PM, < discuss-request at mpich.org [1]> wrote:
>
>
> Send discuss mailing list submissions to discuss at mpich.org [2]
> https://lists.mpich.org/mailman/listinfo/discuss[3]
> discuss-request at mpich.org [1]
> discuss-owner at mpich.org [4]
> sniu at hawk.iit.edu [5]>To: discuss at mpich.org [2]
> CAFNNHkwpqdGfZXctL0Uz3hpeL25mZZMtB93qGXjc_+tjnV4csA at mail.gmail.c
> om[6]>Content-Type: text/plain; charset="iso-8859-1"
>
> Hi,
>
> Sorry to bother you guys on this stupid question. last time I re-install
> OSfor all blades to keep them the same version. after I mount, set
> keylessssh, the terimnal gives the error below:
>
> [ proxy:0:1 at iocfccd3.aps.anl.gov [7]]
> HYDU_sock_connect(./utils/sock/sock.c:174): unable to connect from
> " iocfccd3.aps.anl.gov [8]" to" iocfccd1.aps.anl.gov [9]" (No route to host)
> [ proxy:0:1 at iocfccd3.aps.anl.gov [7]] main (./pm/pmiserv/pmip.c:189):
> unable toconnect to server iocfccd1.aps.anl.gov [9] at port 38242 (check
> for firewalls!)
>
> I can ssh from iocfccd1 to iocfccd3 without password. Should I shut downall
> firewalls on each server? I cannot find out where is the problem. Thankyou
>
> --Best Regards,Sufeng NiuECASP lab, ECE department, Illinois Institute of
> TechnologyTel: 312-731-7219[10]
> http://lists.mpich.org/pipermail/discuss/attachments/20130621/5503b1bc/a
> ttachment-0001.html[11] >
>
> ------------------------------
>
> Message: 2Date: Fri, 21 Jun 2013 10:58:26 -0500From: Antonio J. Pe?a
> < apenya at mcs.anl.gov [12]>To: discuss at mpich.org [2]
> iocfccd1.aps.anl.gov [9]" from iocfccd3?[1]
>
> Antonio
>
>
> On Friday, June 21, 2013 10:51:50 AM Sufeng Niu wrote:
>
>
> Hi,
>
>
> Sorry to bother you guys on this stupid question. last time I re-install OS
> forall blades to keep them the same version. after I mount, set keyless
> ssh,the terimnal gives the error below:
>
>
> proxy:0:1 at iocfccd3.aps.anl.gov [7][2]]
> HYDU_sock_connect(./utils/sock/sock.c:174): unable to connect from
> " iocfccd3.aps.anl.gov [8][3]"to " iocfccd1.aps.anl.gov [9][1]" (No route to
> host)[ proxy:0:1 at iocfccd3.aps.anl.gov [7][2]] main
> (./pm/pmiserv/pmip.c:189):unable to connect to server
> iocfccd1.aps.anl.gov [9][1] at port 38242 (checkfor firewalls!)
>
>
>
> I can ssh from iocfccd1 to iocfccd3 without password. Should I shut downall
> firewalls on each server? I cannot find out where is the problem. Thankyou
>
>
>
>
> -- Best Regards,Sufeng NiuECASP lab, ECE department, Illinois Institute of
> TechnologyTel: 312-731-7219[4]
>
>
> --------[1] _ http://iocfccd1.aps.anl.gov_
> proxy%3A0%3A1 at iocfccd3.aps.anl.gov [13]
> http://iocfccd3.aps.anl.gov [8]
> 312-731-7219[10]
> http://lists.mpich.org/pipermail/discuss/attachments/20130621/01b37902/
> attachment-0001.html[14] >
>
> ------------------------------
>
> Message: 3Date: Sat, 22 Jun 2013 12:49:10 -0400From: Jiri Simsa
> < jsimsa at cs.cmu.edu [15]>To: discuss at mpich.org [2]
> CAHs9ut-_6W6SOHTJ_rD+shQ76bo4cTCuFVAy1f9x-
> J0gioakHg at mail.gmail.com [16]>Content-Type: text/plain;
> charset="iso-8859-1"
>
> Hi,
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