Hi,

m5_checkpoint(delay,period) works the same way as the “m5 checkpoint” command 
(from gem5/util) does in dist-gem5. If you want to initiate the checkpoint from 
your application (by modifying the source code) then you can use 
m5_checkpoint(x,0). If you want to initiate the checkpoint from your OS 
bootscript then you can add “m5 checkpoint  x” to your bootscript.

Regarding DT, you may find some clues in the system terminal log file (by 
default it is in m5out.n/system.terminal where n=[0,N-1] if your dist-gem5 run 
include N gem5 processes).

Regards,
- Gabor

From: gem5-users <gem5-users-boun...@gem5.org> on behalf of Dong Wan Kim 
<dkim.t...@gmail.com>
Reply-To: gem5 users mailing list <gem5-users@gem5.org>
Date: Friday, 9 March 2018 at 16:53
To: gem5 users mailing list <gem5-users@gem5.org>
Subject: Re: [gem5-users] dist-gem5 checkpointing

I see, Gabor.

Sorry that it took some time to reply because I wanted to see if other 
checkpoint option is working (e.g. m5_checkpoint() ) and it looks working.

So, it seems like using function calls such as m5_checkpoint() is "currently" 
right way to do checkpoint dist-gem5 during execution of an application, right?

Also, I have tested checkpointing NPB benchmark that you used in your dist-gem5 
evaluation, but some of them seems not working correctly.
For example, DT terminated with a message like "BAD TERMINATION OF ONE OF YOUR 
APPLICATION PROCESSES", which implies an application was terminated for some 
reason, not because of MPICH (according to MPICH doc. :-) ).
Since you used a subset of NPB suite in your evaluation, do you have some 
insight about why some test cases could not finish successfully and a list of 
those applications?

Thanks.

Dong Wan Kim

On Thu, Mar 8, 2018 at 3:43 AM, Gabor Dozsa 
<gabor.do...@arm.com<mailto:gabor.do...@arm.com>> wrote:
Hi,

dist-gem5 does not support delayed checkpoint currently. The delay option is 
used to decide whether a 'collective' or an 'immediate' checkpoint is to be 
taken.

If delay == 0 then the checkpoint is triggered only when all gem5 instances 
(participating in the dist-gem5 run) have completed an 'm5 checkpoint 0' 
command. An example use case is when one wants to take a checkpoint at a 
synchronisation point in the simulated distributed application (e.g. take a 
checkpoint just before an MPI_Barrier() completes in an MPI application).

On the other hand, if a checkpoint command with a delay != 0 parameter is hit 
in any of the gem5 processes then a checkpoint is taken immediately across all 
participating gem5 instances.

Regards,
Gabor Dozsa

-------------------------

    Date: Wed, 7 Mar 2018 10:21:41 -0600
    From: David Kim <dkim.t...@gmail.com<mailto:dkim.t...@gmail.com>>
    To: gem5 users mailing list 
<gem5-users@gem5.org<mailto:gem5-users@gem5.org>>
    Subject: Re: [gem5-users] dist-gem5 checkpointing
    Message-ID:
                
<caauosrmiikaf9bfe2gudrzrwvtz6he-mtr9bwjtyg5sp393...@mail.gmail.com<mailto:caauosrmiikaf9bfe2gudrzrwvtz6he-mtr9bwjtyg5sp393...@mail.gmail.com>>
    Content-Type: text/plain; charset="utf-8"

    Hello,

    I have looked at the output message again, and it gave the following
    message;
    info: m5 checkpoint called with non-zero delay => triggering immediate
    checkpoint (at the next sync)

    So, I look at the source code that print out that message, and the
    following is the code snippet,

    *@ src/dev/net/dist_iface.cc*

    *bool*
    *DistIface::readyToCkpt(Tick delay, Tick period)*
    *{*
    *    bool ret = true;*
    *    DPRINTF(DistEthernet, "DistIface::readyToCkpt() called, delay:%lu "*
    *            "period:%lu\n", delay, period);*
    *    if (master) {*
    *        if (delay == 0) {*
    *            inform("m5 checkpoint called with zero delay => triggering
    collaborative "*
    *                   "checkpoint\n");*
    *            sync->requestCkpt(ReqType::collective);*
    *        } else {*
    *            inform("m5 checkpoint called with non-zero delay => triggering
    immediate "*
    *                   "checkpoint (at the next sync)\n");*
    *            sync->requestCkpt(ReqType::immediate);*
    *        }*
    *        if (period != 0)*
    *            inform("Non-zero period for m5_ckpt is ignored in "*
    *                   "distributed gem5 runs\n");*
    *        ret = false;*
    *    }*
    *    return ret;*
    *}*

    *@ src/sim/pseudo_inst.cc*

    *void*
    *m5checkpoint(ThreadContext *tc, Tick delay, Tick period)*
    *{*
    *    DPRINTF(PseudoInst, "PseudoInst::m5checkpoint(%i, %i)\n", delay,
    period);*
    *    if (!tc->getCpuPtr()->params()->do_checkpoint_insts)*
    *        return;*

    *    if (DistIface::readyToCkpt(delay, period)) {*
    *        Tick when = curTick() + delay * SimClock::Int::ns;*
    *        Tick repeat = period * SimClock::Int::ns;*
    *        exitSimLoop("checkpoint", 0, when, repeat);*
    *    }*
    *}*

    Since the checkpoint delay is non-zero value, it seems to force do
    checkpointing at the next sync time rather than delay value.
    In this simulation, I added 'dist-sync-start=1000000000000t', so I think
    sync will be on every 1s in simulation time, right?

    FYI, I have added 'echo' command, but it was not printed out, so I think
    simulation did not reach that point.

    Can you explain what is exactly happening in the dist-gem5 checkpoint
    routine? Any suggestion or idea will be appreciated.

    Thanks.

    Dong Wan Kim


    On Mon, Mar 5, 2018 at 6:01 PM, Mohammad Alian 
<m.alian1...@gmail.com<mailto:m.alian1...@gmail.com>>
    wrote:

    > Hi,
    >
    > What you have should work. Are you sure that you start the application
    > after the checkpoint command (you don't block any where?)? E.g. what would
    > be the output if you add an echo right before starting the MPI app:
    >
    > /sbin/m5 checkpoint 50000000000000
    >
    > /sbin/m5 loadsymbol
    >
    > /sbin/m5 resetstats
    > *echo "start the app"*
    > mpiexec -hosts=node1,node2 -np 2 ./cg.S.2
    >
    >
    > Do you see immediate progress in your application if you remove "/sbin/m5
    > checkpoint 50000000000000"?
    >
    > Best,
    > Mohammad
    >
    >
    > On Mon, Mar 5, 2018 at 11:59 AM, David Kim 
<dkim.t...@gmail.com<mailto:dkim.t...@gmail.com>> wrote:
    >
    >> Hello,
    >>
    >> I am trying to checkpoint dist-gem5 in the middle of the execution of the
    >> application.
    >> The following is my script file that used to run dist-gem5 (with 2 nodes)
    >> after boot up Linux.
    >>
    >> < for node 1 (node1.rcS)>
    >> *#!/bin/sh*
    >>
    >> *# Set up IP address for node 1*
    >> */sbin/ifconfig eth0 hw ether 00:90:00:00:00:02*
    >> */sbin/ifconfig eth0 192.168.0.2 netmask 255.255.255.0 up*
    >>
    >> *cd /root/NPB3.3.1/NPB3.3-MPI/bin*
    >>
    >> *#  checkpoint after delay (in ns, so the below delay represents 50000
    >> seconds! I have also tested 0.1s,10s, and 100s delay)*
    >> */sbin/m5 checkpoint 50000000000000*
    >>
    >> */sbin/m5 loadsymbol*
    >>
    >> */sbin/m5 resetstats*
    >> *mpiexec -hosts=node1,node2 -np 2 ./cg.S.2*
    >> */sbin/m5 exit*
    >>
    >> < for node 2  (node2.rcS) >
    >> *#!/bin/sh*
    >>
    >>
    >> * # Set up IP address for node 2 *
    >> */sbin/ifconfig eth0 hw ether 00:90:00:00:00:03*
    >> */sbin/ifconfig eth0 192.168.0.3 netmask 255.255.255.0 up*
    >>
    >> And, here is my commandline to run dist-gem5 (I did not use gem5-dist.sh
    >> for some reason, and the following commandline works well in general)
    >>
    >> *For switch node,*
    >>
    >> *. /build/ARM/gem5.opt -d ./m5out.switch ./configs/dist/sw.py --is-switch
    >> --dist-size=2 --dist-server-name=localhost --dist-server-port=2200*
    >>
    >> *For computer nodes (here is one for node1),*
    >> */build/ARM/gem5.opt -d ./m5out.0 ./configs/example/fs.py
    >> --machine-type=VExpress_EMM64
    >> --disk-image=aarch64-ubuntu-trusty-headless.img
    >> --kernel=vmlinux.aarch64.20140821
    >> --dtb-filename=vexpress.aarch64.20140821.dtb --cpu-type=TimingSimpleCPU
    >> --num-cpus=1 --caches --l2cache --mem-size=512MB --mem-channels=1
    >> --mem-ranks=1 --script=./node1.rcS --dist --dist-rank=0 --dist-size=2
    >> --dist-server-name=localhost --dist-server-port=2200
    >> --dist-sync-start=1000000000000t*
    >>
    >> I have increased checkpoint delay to see if there is any change in my
    >> checkpoint image, but seems to show same behavior; wait that amount of 
time
    >> (not running an application) then do checkpoint (no progress is displayed
    >> on console until checkpoint. Then, restoring gem5 prints out all the
    >> application output from the beginning).
    >>
    >> To checkpoint in the middle of the running of an application, for
    >> example, after 1 billion cycles after running an application, should I 
only
    >> use m5_roi_begin() and m5_roi_end() call in the application's source code
    >> (I did not test this yet, but guess it will work?), but cannot just add
    >> some delay to checkpoint as shown above (and thus not change application
    >> source code)?
    >>
    >> Any comment will be appreciated.
    >>
    >> Thanks.
    >>
    >> Regards,
    >> Dong Wan Kim
    >>
    >> _______________________________________________
    >> gem5-users mailing list
    >> gem5-users@gem5.org<mailto:gem5-users@gem5.org>
    >> http://m5sim.org/cgi-bin/mailman/listinfo/gem5-users
    >>
    >
    >
    > _______________________________________________
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    > gem5-users@gem5.org<mailto:gem5-users@gem5.org>
    > http://m5sim.org/cgi-bin/mailman/listinfo/gem5-users

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