On Thu, Jul 29, 2010 at 07:04:06PM -0400, Ted Ts'o wrote: > My understanding is that "everything FUA" can be a performance > disaster. That's because it bypasses the track buffer, and things get > written directly to disk. So there is no possibility to reorder > buffers so that they get written in one disk rotation. Depending on > the disk, it might even be that if you send N sequential sectors all > tagged with FUA, it could be slower than sending the N sectors > followed by a cache flush or SYNCHRONIZE_CACHE command. Not sure why the discussion is drifting in this direction again, but no one suggested to switch eweryone to forcefully use a FUA only primitive. If we offer a WRITE_FUA primitive to those who can make use of it, it won't mean the the cache flush primitive will go away - we will need it to implement fsync anyway. > -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
