Re: [PATCH] barrier patch set

From: Jeff Garzik
Date: Wed Mar 31 2004 - 16:40:45 EST

Stephen C. Tweedie wrote:

On Tue, 2004-03-30 at 23:21, Jeff Garzik wrote:

For IDE, O_DIRECT and O_SYNC can use special "FUA" commands, which don't return until the data is on the platter.

fsync() is still really nasty, because that can require that we wait on
IO that was submitted by the VM before we knew that there was a
synchronous IO wait coming. SCSI also has an FUA bit that can make a
difference if you've got writeback caching enabled. (And FUA on read
can bypass drive writethrough caches, too, for media verification.)

Agreed, but I did not mention fsync(), since that would not be appropriate to FUA like O_DIRECT or O_SYNC might be.


To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at