gem5缓存统计信息-重置和转储 [英] gem5 cache statistics - reset and dump

问题描述

我正在尝试熟悉gem5模拟器.首先，我用

I am trying to get familiar with gem5 simulator. To start, I wrote a simple program with

int main()
{
    m5_reset_stats(0, 0);
    m5_dump_stats(0, 0);
    return 0;
}

我使用util/m5/m5op_x86.S对其进行了编译，并使用...运行了它.

I compiled it with util/m5/m5op_x86.S and ran it using...

 ./build/X86/gem5.opt configs/example/se.py --caches -c ~/tmp/hello

m5out/stats.txt显示(以及其他内容)...

The m5out/stats.txt shows (among other things)...

system.cpu.dcache.ReadReq_hits::total             881
system.cpu.dcache.WriteReq_hits::total            917
system.cpu.dcache.ReadReq_misses::total            54
system.cpu.dcache.WriteReq_misses::total           42

为什么一个空函数显示如此多的命中和未命中?碰巧是libc引起的吗?如果是这样，那么m5_reset_stats()和m5_dump_stats()的目的是什么?

Why is an empty function showing so much hits and misses? Are the hits and misses caused by libc? If so, then what is the purpose of m5_reset_stats() and m5_dump_stats()?

推荐答案

我将检查stats.txt文件中是否有两个

I would check in the stats.txt file if there are two chunks of

---Begin--- 
---End-----

因为正如您所解释的，模拟器应该将统计信息转储到dump_stats(0,0)和运行结束时.因此，似乎您正在查看其中一个间隔(并且我希望所有统计数据的另一个间隔都为0)；或是模拟中有错误，dump_stats()(或reset_stats())实际上什么也没做.实际上，这确实发生在我身上很多次，但是我不确定这个错误的来源.

because as you explained it, the simulator is supposed to dump the stats at dump_stats(0,0) and at the end of the run. So, it seems like you either are looking at one of those intervals (and I would expect the other interval to have 0 for all stats); or there was a bug in the simulation and the dump_stats() (or reset_stats())didn't actually do anything. That actually happened to me plenty of times, but I am not really sure as to the source of this bug.

如果您想进一步解决问题，可以执行以下操作:

If you want to troubleshoot further, you could do the following:

1. 查看代码的反汇编并找到reset_stats.w和dump_stats.w
2. 从gem5转储跟踪，并查看它是否最终执行了转储和重置指令，以及之前/之后执行了哪些指令(以及多少).

希望这会有所帮助！

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