gem5 101 Homeworkをやってみる (1. 単純な実験)

gem5への理解を深めるために、以下のネット上に公開されている課題をやってみようと思う。

www.gem5.org

まずは、エラトステネスの篩を実装して、コンパイルして実行してみる。 エラトステネスの篩の実装を忘れてしまったので、とりあえずネット上のソースコードを検索して、あとはuint64_tに拡張してやってみる。

#include <stdint.h>
#include <stdio.h>
#include <math.h>

int main (int argc, char *argv[]){
    uint64_t num = atol(argv[1]);
    uint64_t *prime = new uint64_t[num+1];
    uint64_t i, j;

    for(uint64_t i=2;i<=num;i++){
        prime[i] = 1;
    }

    uint64_t limit = (uint64_t)sqrt(num);

    for (uint64_t i=2; i<=limit; i++){
        if(prime[i] == 1){
            for (uint64_t j = 2*i; j<=num; j++){
                if(j%i==0){
                    prime[j]=0;
                }
            }
        }
    }

    uint64_t index = 0;

    for(uint64_t i=2; i<=num; i++) {
        if(prime[i]==1){
            index++;
        }
    }
    printf ("%ld\n", index);

}

$ g++ eratosthenes.cc -O3 -o eratosthenes.x86 # x86用にコンパイル
$ riscv64-unknown-elf-g++ -O3 eratosthenes.cc -o eratosthenes.riscv

とりあえずx86で確認しておく。

$ ./eratosthenes.x86 100000000
5761455

$ ../gem5_myriscvx/build/RISCV/gem5.opt ../gem5_myriscvx/configs/deprecated/example/se.py -c eratosthenes.riscv -o 100000000

command line: ../gem5_myriscvx/build/RISCV/gem5.opt ../gem5_myriscvx/configs/deprecated/example/se.py -c eratosthenes.riscv -o 100000000

warn: The `get_runtime_isa` function is deprecated. Please migrate away from using this function.
warn: The se.py script is deprecated. It will be removed in future releases of  gem5.
warn: The `get_runtime_isa` function is deprecated. Please migrate away from using this function.
Global frequency set at 1000000000000 ticks per second
warn: No dot file generated. Please install pydot to generate the dot file and pdf.
src/mem/dram_interface.cc:690: warn: DRAM device capacity (8192 Mbytes) does not match the address range assigned (512 Mbytes)
src/arch/riscv/linux/se_workload.cc:60: warn: Unknown operating system; assuming Linux.
src/base/statistics.hh:279: warn: One of the stats is a legacy stat. Legacy stat is a stat that does not belong to any statistics::Group. Legacy stat is deprecated.
system.remote_gdb: Listening for connections on port 7000
**** REAL SIMULATION ****
src/sim/simulate.cc:194: info: Entering event queue @ 0.  Starting simulation...
src/sim/mem_pool.cc:120: fatal: fatal condition freePages() <= 0 occurred: Out of memory, please increase size of physical memory.
Memory Usage: 610204 KBytes

あれ、メモリ不足で落ちてしまった。これは課題の通りのオプションなんだけど、ちょっとやりすぎたのかな。

$ ../gem5_myriscvx/build/RISCV/gem5.opt ../gem5_myriscvx/configs/deprecated/example/se.py -c eratosthenes.riscv -o 10000000