Comment 300 for bug 620074

I have the same result here when mouting with the "sync" option.

I try also async and ionice -c1 'pidof kjournald' and doesn't seems to improve latency measured by fsync-tester.

(In reply to comment #280)
> 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?