I tried lmbench 1.9 on an ultra5 (270 MHz, 128 MB RAM)
running linux 2.2.2 and compared with an identical machine running
solaris 2.6(except it had 64M). linux blew solaris away in most of
the benchmarks except mmap latency.
...
so what's up with mmap ?
There are two things which changed in the mmap/munmap code paths
recently, and I know the numbers were competitive when I was running
lmbench a lot several months ago.
The two changes are:
1) Using VMA trees (I really don't think it accounts for the slowness
being seen here)
2) The freeing up of page tables at munmap
I think #2 could be a possible culprit.
Linus, did you see any performance degration of lat_mmap when you
added the free_pgtables() stuff into 2.2.x? I think such a problem
would trigger if lat_mmap is doing large enough mmap's and they are in
the right place.
Mr Ganesh, can you post here the full lmbench raw output for the
lat_mmap test? It should be in the results/sparc64-linux/xxxx files
lmbench made as it ran.
Later,
David S. Miller
davem@redhat.com
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.rutgers.edu
Please read the FAQ at http://www.tux.org/lkml/