On Thu, Sep 25, 2008 at 02:08:23PM -0400, Joe Landman wrote: > It looks like people use mmap files to explicitly avoid seeks, > replacing semantics of file IO with memory access semantics.
Well, it explicitly avoids having to call I/O functions all the time as you skip around a file. It also is better at sharing, if several processes have the same file open, or if the file was just written. Remember that read() usually has to copy the data. mmap() sometimes reduces the number of copies. > Sadly, mmap > on linux uses the paging mechanism which is pretty much stuck at 4kB > pages for most distributions. I think the SiCortex folks and a few > others are working with 64 kB page kernels. That's a function of architecture. The Linux mips and powerpc ports have supported larger-than-4k pages for a long time -- it's easy to do if you pick a single page-size at boot. x86 only has Overly Small and Really Too Huge pages. -- greg _______________________________________________ Beowulf mailing list, Beowulf@beowulf.org To change your subscription (digest mode or unsubscribe) visit http://www.beowulf.org/mailman/listinfo/beowulf
