Re: [PATCH] readahead: initial method - expected read size - fix fastcall

Fengguang Wu
2006-06-08T08:13:56Z

It's interesting that copying of sparse file is more efficient with small
readahead size :) I get the same conclusion, though with smaller differences:

SUMMARY
user sys cpu total
ARA, 1M 0.15 6.28 82.80 7.73
ARA, 128k 0.14 6.09 85.60 7.26
STOCK, 128k 0.15 6.05 85.60 7.22

TEST CASE

wfg ~% ll work/sparse
-rw-r--r-- 1 wfg wfg 1.6G 2006-05-21 15:11 work/sparse
wfg ~% free
total used free shared buffers cached
Mem: 501 496 5 0 5 191
-/+ buffers/cache: 300 201
Swap: 127 0 127

wfg ~% time cp work/sparse /dev/null

ARA, 1M
cp work/sparse /dev/null 0.15s user 6.35s system 80% cpu 8.125 total
cp work/sparse /dev/null 0.14s user 6.28s system 84% cpu 7.556 total
cp work/sparse /dev/null 0.14s user 6.25s system 82% cpu 7.744 total
cp work/sparse /dev/null 0.15s user 6.23s system 85% cpu 7.495 total
cp work/sparse /dev/null 0.16s user 6.30s system 83% cpu 7.719 total

ARA, 128k
cp work/sparse /dev/null 0.15s user 6.07s system 86% cpu 7.224 total
cp work/sparse /dev/null 0.15s user 6.05s system 84% cpu 7.334 total
cp work/sparse /dev/null 0.14s user 6.18s system 86% cpu 7.328 total
cp work/sparse /dev/null 0.13s user 6.11s system 86% cpu 7.217 total
cp work/sparse /dev/null 0.14s user 6.06s system 86% cpu 7.179 total

STOCK, 128k
cp work/sparse /dev/null 0.16s user 6.01s system 86% cpu 7.162 total
cp work/sparse /dev/null 0.14s user 6.10s system 86% cpu 7.222 total
cp work/sparse /dev/null 0.14s user 6.04s system 86% cpu 7.186 total
cp work/sparse /dev/null 0.15s user 6.02s system 85% cpu 7.210 total
cp work/sparse /dev/null 0.14s user 6.09s system 85% cpu 7.320 total

Wu