O_DIRECT|O_SYNC semantics?

[Zoltan Arnold NAGY]

Hi,

Could someone have a look here:
http://serverfault.com/questions/520141/please-explain-my-fio-results-is-o-synco-direct-misbehaving-on-linux

Basically, I'm seeing wastly different results on Linux and on FreeBSD 9.1.
Either FreeBSD's not honoring O_SYNC properly, or Linux does something
wicked.

I've been at it for a few days, without any real progress.

I do realize that since I'm operating at a block device level not with any
filesystem it's strange to ask on -fs, but I came to this results while
experimenting with the SSD as a ZIL device, and was surprised at the low
numbers.

Thanks,
Zoltan