Prompted by Hamid's question about simulation speed comparison with MARSS, I wrote a small benchmark (see bottom of this email), then compiled and ran it within the gem5 full system emulation using the disk image http://www.gem5.org/dist/current/arm/arm-system-2011-08.tar.bz2 The gem5 configuration is with all the defaults, build/ARM/gem5.opt configs/example/fs.py --disk-image=/home/bpayne/full_system_for_gem5/disks/arm-ubuntu-natty-headless.img
The boot time for full simulation mode (how long until I'm at the login terminal via telnet) is 23 minutes. In full simulation mode, I see the following output (my binary is called "a.out") root@gem5sim:~# date; time ./a.out; date date; time ./a.out; date Wed Dec 31 20:49:26 CST 1969 CPU time= 0.210000 seconds real 0m0.216s user 0m0.060s sys 0m0.150s Wed Dec 31 20:49:27 CST 1969 root@gem5sim:~# The wall clock time (how long I wait for the simulated system) is about 4 minutes. Thus the slowdown is a factor of (4*60)/.2=1200, which is consistent with previous runs I've done. Next I ran the same code in syscall emulation mode, cross compiled using Linaro for ARM. This took 168 seconds of wall clock time and 0.07 seconds of simulated time, a ratio of (2*60+48)/0.07=2400 [twice as fast as full system emulation!]. I repeated the same measure with bench.c cross-compiled for ARM using Mentor Graphics Sourcery Tools. The syscall emulation took 162 wall clock seconds and 0.06 simulation seconds, a ratio of 2700. [These numbers may be somewhat inaccurate due to the low simulation time.] Below is how I captured the times in syscall emulation mode. bpayne@bpayne-VirtualBox64:~/gem5$ date; time build/ARM/gem5.opt configs/example/se.py -c tests/test-progs/bens_benchmark/bin/arm/bench_linaro.lex ; date Wed Oct 24 08:24:13 EDT 2012 gem5 Simulator System. http://gem5.org gem5 is copyrighted software; use the --copyright option for details. gem5 compiled Oct 16 2012 13:57:10 gem5 started Oct 24 2012 08:24:13 gem5 executing on bpayne-VirtualBox64 command line: build/ARM/gem5.opt configs/example/se.py -c tests/test-progs/bens_benchmark/bin/arm/readwrite_linaro.lex Global frequency set at 1000000000000 ticks per second 0: system.remote_gdb.listener: listening for remote gdb #0 on port 7000 **** REAL SIMULATION **** info: Entering event queue @ 0. Starting simulation... CPU time= 0.070000 seconds hack: be nice to actually delete the event here Exiting @ tick 73563381000 because target called exit() real 2m48.492s user 1m47.319s sys 0m2.792s Wed Oct 24 08:27:01 EDT 2012 bpayne@bpayne-VirtualBox64:~/gem5$ ************************************** Next I ran the same bench.c code in MARSS using the system image http://bertha.cs.binghamton.edu/downloads/ubuntu-natty.tar.bz2 The boot time for full simulation mode of MARSS (how long until I'm at the login terminal via VNC) is 42 seconds (33 times faster than gem5). I compiled a static binary of bench.c and ran it in MARSS: root@ubuntu:~# date; time ./bench.lex ; date Wed Oct 24 14:38:25 UTC 2012 CPU time= 8.66 seconds real 0m8.752s user 0m1.200s sys 0m7.490s Wed Oct 24 14:38:34 UTC 2012 root@ubuntu:~# The wall clock time for this simulation is roughly 9 seconds. The CPUs are different, so it doesn't make sense to compare MARSS's 8.66 seconds to gem5's 0.07 seconds. What is relevant is the slowdown factor -- 1 for MARSS, between 1200 and 2700 for gem5. ************************************** All of these timings were carried out in Ubuntu 12.04 64bit running in a single CPU VirtualBox, hosted by Ubuntu 12.04 64bit with Intel Core i7 930 @ 2.80 Ghz. The host system has 6GB of RAM, and the VirtualBox has 2GB. "bench.c" is a program to load the CPU and file I/O /* benchmark * 20121018 * Ben Payne * load CPU and file I/O */ #include <stdio.h> #include <time.h> main() { int number_of_computes; int number_of_read_writes; int number_of_iterations; int iteration_indx; int read_write_indx; int compute_indx; int valu; int temp_read; clock_t time_start, time_end; double cpuTime; FILE *outfile; FILE *infile; time_start = clock(); number_of_computes=500; number_of_read_writes=100; number_of_iterations=100; for (iteration_indx = 1; iteration_indx <= number_of_iterations ; iteration_indx++) { for (read_write_indx = 1; read_write_indx <= number_of_read_writes ; read_write_indx++) { outfile = fopen("out.dat","a+"); /* apend file (add text to a file or create a file if it does not exist.*/ fprintf(outfile,"%u\n",read_write_indx); /*writes*/ fclose(outfile); for (compute_indx = 1; compute_indx <= number_of_computes ; compute_indx++) { valu=(compute_indx+1)*23; } infile = fopen("out.dat","r"); fscanf(infile,"%d",&temp_read); fclose(infile); } } time_end = clock(); cpuTime= ((double)(time_end-time_start))/ (CLOCKS_PER_SEC); printf("CPU time= %f seconds\n",cpuTime); return 0; } From: gem5-users-boun...@gem5.org [mailto:gem5-users-boun...@gem5.org] On Behalf Of Hamid Reza Khaleghzadeh Sent: Tuesday, October 23, 2012 10:26 AM To: gem5 users mailing list Subject: Re: [gem5-users] gem5 versus MARSS Thanks for your answer. Ruby is a module in GEM5 which simulate memory hierarchy. Suppose there is an application that its execution time is 20 ms on a real system. GEM5 simulate the application in about 15 min. Hos is MARSS86 simulation speed? On Tue, Oct 23, 2012 at 5:27 PM, Payne, Benjamin <bpa...@lps.umd.edu> wrote: Hello, I'm not familiar with what you are referring to by the ruby module - is that an addon for Gem5? You have a good question, but how would I quantify the difference in simulation speeds between MARSS and Gem5? Is there an established benchmark to run? Kindly, Ben Payne From: gem5-users-boun...@gem5.org [mailto:gem5-users-boun...@gem5.org] On Behalf Of Hamid Reza Khaleghzadeh Sent: Tuesday, October 23, 2012 9:31 AM To: gem5 users mailing list Subject: Re: [gem5-users] gem5 versus MARSS I have a question about MARSS. As you know GEM5 simulation speed with ruby module is very slow. May I know MARSS simulation speed? Thanks On Tue, Oct 23, 2012 at 2:26 AM, Andreas Hansson <andreas.hans...@arm.com> wrote: Hi Benjamin, The list is long.gem5 has (amongst other things): a variety of CPU models that are orthogonal to the ISA, atomic for speed, in order and O3 for details uarch models BSD license (thus both academia and companies involved and contributing) full-system ready-to-run Android disk images and configurations, not just your average chip-multi-processor, but also heterogeneous application-processor-like systems with state-of-the-art CPU models a very active (and large) user community Ultimately using one or the other really depends on what problem it is you want to address. Andreas From: <Payne>, Benjamin <bpa...@lps.umd.edu<mailto:bpa...@lps.umd.edu>> Reply-To: gem5 users mailing list <gem5-users@gem5.org<mailto:gem5-users@gem5.org>> Date: Monday, 22 October 2012 22:06 To: "gem5-users@gem5.org<mailto:gem5-users@gem5.org>" <gem5-users@gem5.org<mailto:gem5-users@gem5.org>> Subject: [gem5-users] gem5 versus MARSS Hello, What is the difference between gem5 http://gem5.org/Main_Page and MARSS (Micro-ARchitectural and System Simulator for x86-based Systems) http://marss86.org/~marss86/index.php/Home As far as I can tell, -gem5 can support Alpha, ARM, SPARC, and x86 instruction set architectures, whereas MARSS is only for x86. -gem5 can be integrated into Structural Simulation Toolkit, whereas MARSS has not been -both gem5 and MARSS can simulate multiple cores -both gem5 and MARSS can use DRAMSim2 Please correct me if any of these statements are incorrect. Are there any other considerations? Thank you, Ben Payne http://mst.edu/~bhpxc9/ Suite 450, Room S452 5520 Research Park Drive Catonsville, MD 21228-4870 Laboratory for Physical Sciences http://www.lps.umd.edu/ office: 443-654-7890 cell: 608-308-2413 -- IMPORTANT NOTICE: The contents of this email and any attachments are confidential and may also be privileged. If you are not the intended recipient, please notify the sender immediately and do not disclose the contents to any other person, use it for any purpose, or store or copy the information in any medium. Thank you. _______________________________________________ gem5-users mailing list gem5-users@gem5.org http://m5sim.org/cgi-bin/mailman/listinfo/gem5-users -- Hamid Reza Khaleghzadeh http://hkhaleghzadeh.webs.com _______________________________________________ gem5-users mailing list gem5-users@gem5.org http://m5sim.org/cgi-bin/mailman/listinfo/gem5-users -- Hamid Reza Khaleghzadeh http://hkhaleghzadeh.webs.com _______________________________________________ gem5-users mailing list gem5-users@gem5.org http://m5sim.org/cgi-bin/mailman/listinfo/gem5-users
