PTE_CACHE_WRITE_ALLOCATE 1

2chでやってみる人が出てきたようなので、前に計った結果を残しておこう。

コマンド find / hdparm apache2 memtest
-tT restart 12M 1
適用前
real 3m9.441s 0m13.330s 0m2.341s 6m24.142s
user 0m2.410s 0m0.410s 0m0.570s 6m22.380s
sys 0m9.220s 0m3.380s 0m0.390s 0m0.880s
適用後
real 3m21.020s 0m13.369s 0m2.390s 6m22.158s
user 0m2.150s 0m0.630s 0m0.580s 6m20.240s
sys 0m8.440s 0m3.300s 0m0.380s 0m0.970s

# hdparm -tT /dev/hda
適用前
Timing cached reads: 776 MB in 2.00 seconds = 388.00 MB/sec
Timing cached reads: 776 MB in 2.00 seconds = 388.00 MB/sec
Timing cached reads: 776 MB in 2.00 seconds = 388.00 MB/sec
Timing buffered disk reads: 150 MB in 3.02 seconds = 49.67 MB/sec
Timing buffered disk reads: 150 MB in 3.00 seconds = 50.00 MB/sec
Timing buffered disk reads: 150 MB in 3.01 seconds = 49.83 MB/sec
適用後
Timing cached reads: 772 MB in 2.00 seconds = 386.00 MB/sec
Timing cached reads: 780 MB in 2.00 seconds = 390.00 MB/sec
Timing cached reads: 776 MB in 2.00 seconds = 388.00 MB/sec
Timing buffered disk reads: 152 MB in 3.02 seconds = 50.33 MB/sec
Timing buffered disk reads: 152 MB in 3.03 seconds = 50.17 MB/sec
Timing buffered disk reads: 152 MB in 3.00 seconds = 50.67 MB/sec

必ずしも速くなるというわけではない。内容によっては、結果が遅くなることすらある。