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SubjectRe: [PATCH 00/23] per device dirty throttling -v8
On Sun, 5 August 2007 20:37:14 +0200, Jörn Engel wrote:
> Guess I should throw in a kernel compile test as well, just to get a
> feel for the performance.

Three runs each of noatime, relatime and atime, both with cold caches
and with warm caches. Scripts below. Run on a Thinkpad T40, 1.5GHz,
2GiB RAM, 60GB 2.5" IDE disk, ext3.

Biggest difference between atime and noatime (median run, cold cache) is
~2.3%, nowhere near the numbers claimed by Ingo. Ingo, how did you
measure 10% and more?

noatime, cold cache relatime, cold cache atime, cold cache

real 2m10.242s real 2m10.549s real 2m10.388s
user 1m46.886s user 1m46.680s user 1m47.000s
sys 0m8.243s sys 0m8.423s sys 0m8.239s

real 2m11.270s real 2m11.212s real 2m14.280s
user 1m46.940s user 1m46.776s user 1m46.670s
sys 0m8.139s sys 0m8.283s sys 0m8.503s

real 2m11.601s real 2m14.861s real 2m14.335s
user 1m46.920s user 1m47.103s user 1m46.846s
sys 0m8.246s sys 0m8.266s sys 0m8.349s

noatime, warm cache relatime, warm cache atime, warm cache

real 1m55.894s real 1m56.053s real 1m56.905s
user 1m46.683s user 1m46.600s user 1m46.853s
sys 0m8.186s sys 0m8.349s sys 0m8.249s

real 1m55.823s real 1m56.093s real 1m57.077s
user 1m46.583s user 1m46.913s user 1m46.590s
sys 0m8.259s sys 0m7.966s sys 0m8.523s

real 1m55.789s real 1m56.214s real 1m57.224s
user 1m46.803s user 1m46.753s user 1m46.953s
sys 0m8.053s sys 0m8.113s sys 0m8.113s


Data expands to fill the space available for storage.
-- Parkinson's Law

Cold cache script:
make distclean
echo 1 > /proc/sys/vm/drop_caches
echo 2 > /proc/sys/vm/drop_caches
echo 3 > /proc/sys/vm/drop_caches
make allnoconfig
time make

Warm cache script:
make distclean
make allnoconfig
rgrep laksdflkdsaflkadsfja .
time make
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