ATA flush cache on sync()

R. B. Riddick arne_woerner at
Sat Sep 2 09:43:19 UTC 2006

--- hardware at wrote:
> When the sync() system call is called on an ATA drive with a UFS 2
> filesystem, is the "FLUSH CACHE" ATA command sent to the drive?
As far as I know, when sync() return u cannot even be sure, that the in-kernel
buffers are flushed already...

And the "FLUSH CACHE" ATA command (or BIO_FLUSH since gjournal) is disputed,
since it might break (in FBSD not implemented) concepts like TCQ(?) (tagged
command queuing) or so...

But I think there should be a FLUSH CACHE command from time to time, so that
there cannot be an arbitrary gap...


Do You Yahoo!?
Tired of spam?  Yahoo! Mail has the best spam protection around 

More information about the freebsd-fs mailing list