Re: Efficient IPC mechanism on Linux

[Pavel Machek <pavel@ucw.cz>]

Hi!

> > Can you make it available so we can test on, say, 900MHz athlon? Or
> > you can have it tested on 1800MHz athlon64, that's about as high end
> > as it can get.
> 
> I just deleted the program, so here's a rewrite :)
> 
> 	#include <sys/mman.h>
> 
> 	int main()
> 	{
> 		int i, j;
> 		for (j = 0; j < 64; j++) {
> 			volatile char * ptr =
> 				mmap (0, 4096 * 4096, PROT_READ | PROT_WRITE,
> 				      MAP_PRIVATE | MAP_ANON, -1, 0);
> 			for (i = 0; i < 4096; i++) {
> 	#if 1
> 				*(ptr + 4096 * i) = 0; /* Write */
> 	#else
> 				(void) *(ptr + 4096 * i); /* Read */
> 	#endif
> 			}
> 			munmap ((void *) ptr, 4096 * 4096);
> 		}
> 		return 0;
> 	}
> 
> Smallest results, from "gcc -o test test.c -O2; time ./test" on a
> 1500MHz dual Athlon 1800 MP:
> 
> Write:
> 	real	0m1.316s
> 	user	0m0.059s
> 	sys	0m1.256s
> 
> 	==> 7531 cycles per page
> 
> Read:
> 	real	0m0.199s
> 	user	0m0.053s
> 	sys	0m0.146s
> 
> 	==> 1139 cycles per page
> 
> As I said, it's a crude upper bound.

But you should also time memory remapping stuff on same cpu, no?

							Pavel
-- 
When do you have a heart between your knees?
[Johanka's followup: and *two* hearts?]