I would like ask for adding a feature to the mmap system call.
During the compilation of MPICH (a library for parallel processing by
message passing) I found that it cannot work at full performance under
Linux because of a limitation of the mmap system call. For this reason,
MPICH cannot take full advantadge of a SMP machine under Linux.
./configure --with-device=ch_mem
[other messages]
mem = (char *) mmap((caddr_t) 0, memsize,
PROT_READ|PROT_WRITE|PROT_EXEC,
MAP_SHARED|MAP_ANONYMOUS,
-1, (off_t) 0);
According to the library documentation, "Linux does not support standard
mmap system call". I cannot say if this is accurate of not. I know that
this system call works without problem under Solaris.
Anyway, supporting the mmap system call with this flags would increase
the performance of SMP Linux boxes with the MPI library. This library
is widely used in the scientific community. Therefore, this enhancement
would be very appreciated.
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