On Sun, Aug 7, 2011 at 1:31 PM, avadh patel <[email protected]> wrote:
> > > On Sat, Aug 6, 2011 at 6:47 PM, Zhe Wang <[email protected]> wrote: > >> Hi, >> >> I am using marss with DRAMsim2 to run the experiment to test memory >> performance. >> >> I would like to set the memory size to 16G. But I found if I set the >> memory size larger than 12000M, the qemu is abort. So I am wondering is >> there any way to set the memory size larger than 12000m? >> >> QEMU doesn't allow VM memory size to be greater than Host memory size. So > you can run simulations of 16 GB RAM only if your host has 16GB or more RAM. > If this is not the case then, does unmodified QEMU allows you to allocate > more than 12GB? > > >> I also did some tests that set the memory size to 8G, then when the >> simulator running the spec2006 benchmark, I print out the physical address, >> I found some of the physical address is 34 bis(binary) that means the >> physical address is larger than 8G. I am confused by this, since if the >> memory size is 8G, all the physical address should within 8G(33 binary >> bits). Is anybody could give me some help on these questions? >> >> This is interesting. Please can you give some example memory addresses? > Even with 8GB RAM, there can be memory access to IO devices via MMIO which > can be mapped to higher memory range. In ptl-qemu.cpp, 'check_and_translate' > function set 'mmio' flag if the requested address belongs to MMIO range. You > can use that function to check if your virtual address is MMIO or not (in > QEMU there is no way to check if physical address is MMIO or not). > Jim, Ishwar, and Mu-Tien have actually run across some out of bound addresses as well -- I didn't get a chance to look to see if the MMIO addresses actually generate cache requests. If I'm not mistaken, the MMIO flag is a reference that gets passed back to the caller -- so theoretically the code that generates the call could propagate this information all the way back to the core so it won't generate cache access for MMIO accesses. That way, DRAMSim will never see MMIO addresses. Or, if check and translate has no side effects, just check the address before generating a cache request. > > - Avadh > >> >> Thank you! >> zhe >> >> _______________________________________________ >> http://www.marss86.org >> Marss86-Devel mailing list >> [email protected] >> https://www.cs.binghamton.edu/mailman/listinfo/marss86-devel >> >> > > _______________________________________________ > http://www.marss86.org > Marss86-Devel mailing list > [email protected] > https://www.cs.binghamton.edu/mailman/listinfo/marss86-devel > >
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