Messages in this thread | | | Date | Wed, 14 Jul 2004 12:57:04 -0400 (EDT) | From | "Richard B. Johnson" <> | Subject | Re: question about ramdisk |
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On Wed, 14 Jul 2004 lya755@ece.northwestern.edu wrote:
> Thanks so much for the hint! Really appreciate it. I'll try out your > suggestions. > > I am still a bit confused, though. If the code is in ramdisk, then it will be > mapped to the process address space, which as I understand, does not involve > any actual data copy and transfer. This sounds very reasonable. But what if > the code is in hard disk? Would the kernel copy it to memory (somewhere > allocated) then map this region as the text section for the address space, and > then run the instructions from ram? That's the way I understand it, but I > don't know whether that is correct. > > Thanks! > Lei
The instructions are always executed from RAM even if the executable file is on a physical disk. The file is memory-mapped. Execute `man mmap`. One of the parameters is MAP_FILE. The whole file is mapped, however, only that which is necessary at a particular time is actually read from the disk, one page at a time.
Cheers, Dick Johnson Penguin : Linux version 2.4.26 on an i686 machine (5570.56 BogoMips). Note 96.31% of all statistics are fiction.
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