Hi All,
I am sorry for the confusion.
I am looking to run a multithreaded application on a mesh of 3x3 CPUs,
where the benchmark spawns 9 threads and each thread runs on
a single CPU (1:1). I went through the past discussions on this mailing
list and saw that m5threads was needed to do this. I have some questions.
(1) If there are 9 CPU, and the host CPU launches 9 threads, then are 8
threads launched on the remaining 8 CPUs and the 9th thread has to wait for
a
thread to complete to begin execution. If not then where does it run as all
the 9 CPUs are currently running a thread (1 host + 8 threads).
(2) Anthony Gutierrez said that m5threads is no longer needed. Is that
correct for gem5-21 ?
(Subject: Simulating multiprogrammed & multithreaded workloads in SE
mode?)
(3) Right now I am trying to build PARSEC 3.0 benchmarks with m5threads,
but I am receiving some errors as follows and I am not sure why:
*base_dir/local/gcc/bin/gcc -O3 -g -funroll-loops -fprefetch-loop-arrays
base_dir/gem5dev/parsec-3.0/pkgs/pthread.o -static-libgcc
-Wl,--hash-style=both -Wl,--as-needed -DPARSEC_VERSION=3.0-beta-20150206 -o
siman_tsp siman_tsp.o -L base_dir/local/gcc/lib64 -L
base_dir/local/gcc/lib ./.libs/libgslsiman.a ../rng/.libs/libgslrng.a
../ieee-utils/.libs/libgslieeeutils.a ../err/.libs/libgslerr.a
../sys/.libs/libgslsys.a ../utils/.libs/libutils.a -lpthread
-lmbase_dir/gem5dev/parsec-3.0/pkgs/pthread.o: In function
`__pthread_initialize_minimal':pthread.c:(.text+0x97): undefined reference
to `_dl_phdr'pthread.c:(.text+0xd9): undefined reference to `_dl_phnum'*
Generally how should I go about integrating the m5thread with any
benchmark?
(4) Also, what other CPU benchmarks are recommended which are multithreaded
and can be run in a manner where I can
launch a thread on each CPU ?
Thank You,
John Smith
<https://www.mail-archive.com/search?l=gem5-users@gem5.org&q=from:%22Gutierrez%2C+Anthony%22>
On Fri, Apr 16, 2021 at 1:50 AM Gabe Black via gem5-users <
gem5-users@gem5.org> wrote:
> That's essentially right, although gem5 does have some plumbing to run
> multiple event queues within the same simulation which can coordinate with
> each other within a small window (quantum) of time. gem5 has support for
> fibers/threads/coroutines, but these are not typically used to model
> events. Events are processed inline when they happen using a simple
> function call.
>
> Gabe
>
> On Thu, Apr 15, 2021 at 2:46 AM gabriel.busnot--- via gem5-users <
> gem5-users@gem5.org> wrote:
>
>> Hi John,
>>
>> Short answer : no, you can only run several simulations in parallel, but
>> not a single simulation using one thread per CPU.
>>
>> Gem5 relies on Discrete Event Simulation (DES) to simulate the concurrent
>> behavior of HW.
>> DES is intrinsically sequential in its execution as it relies on
>> coroutines (also called user user threads, greed threads, fibers, etc.).
>> Parallelizing such application is a very hard task that often requires a
>> lot of subtle code transformations to efficiently protect shared resources.
>> If done correctly, then parallel DES does not have all the good
>> properties of classic DES, especially determinism... Unless you add extra
>> care to preserve it, which is hard, too. Trust me ;).
>>
>> This question has been discussed back in the days but seems stalled now:
>> http://www.m5sim.org/Parallel_M5
>>
>> Cheers,
>> Gabriel
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