Comment 315 for bug 595047

Hi Guys,

After reading those LKML messages from Theoodre, regarding his sync patches, it gave me an idea. Why not just mount my filesystem with "sync" mount option.

I run the following command on one console...
dd if=/dev/zero of=/tmp/bigfile bs=1M count=10000

And Theodore's fsync-test on another. On the standard test, WITHOUT mounting with sync, I get these results out of Theodore's test...

fsync time: 1.5693
fsync time: 18.8047
fsync time: 21.2672
fsync time: 18.6747
fsync time: 2.3821
fsync time: 2.0494
fsync time: 2.8781
fsync time: 21.6300

Here's a "vmstat 1" snipette. All the lines while the dd is running are roughly the same.
 2 9 380388 16716 33412 1409988 0 0 0 15340 806 1188 3 4 0 93
 0 8 380388 15748 33428 1411080 0 0 0 16284 1165 2350 7 8 0 85
 0 9 380388 16620 33432 1409752 0 0 0 18240 878 1108 5 3 0 92
 1 8 380388 16776 33452 1410108 0 0 0 11888 1046 1140 10 8 0 82

When I do the following...
mount -o remount,rw,sync /dev/s/sys /

I get the following benches while running the same dd command...
fsync time: 0.0067
fsync time: 0.0369
fsync time: 0.0208
fsync time: 0.0099
fsync time: 0.1175
fsync time: 0.0337
fsync time: 0.0003
fsync time: 0.0219
fsync time: 0.0110
fsync time: 0.0142
fsync time: 0.0076
fsync time: 0.0146
fsync time: 0.0153
fsync time: 0.1104
fsync time: 0.0061
fsync time: 0.0003

With "vmstat 1" snippet of ...
 1 0 380624 1112236 93104 297252 0 0 0 13056 920 1167 5 3 49 43
 0 1 380624 1098212 93252 311044 0 0 0 15876 925 1165 5 4 52 38
 1 2 380624 1085796 93408 323296 0 0 0 13800 996 1239 10 4 47 38

Did something in the kernel change a couple years ago, in regard to syncing?