On Mon 27-06-11 12:01:40, Ted Tso wrote: > On Mon, Jun 27, 2011 at 05:30:11PM +0200, Lukas Czerner wrote: > > > I've found some. So although data=journal users are minority, there are > > > some. That being said I agree with you we should do something about it > > > - either state that we want to fully support data=journal - and then we > > > should really do better with testing it or deprecate it and remove it > > > (which would save us some complications in the code). > > > > > > I would be slightly in favor of removing it (code simplicity, less options > > > to configure for admin, less options to test for us, some users I've come > > > across actually were not quite sure why they are using it - they just > > > thought it looks safer). > > Hmm... FYI, I hope to be able to bring on line automated testing for > ext4 later this summer (there's a testing person at Google is has > signed up to work on setting this up as his 20% project). The test > matrix that I have him included data=journal, so we will be getting > better testing in the near future. Good! > At least historically, data=journalling was the *simpler* case, and > was the first thing supported by ext4. (data=ordered required revoke > handling which didn't land for six months or so). So I'm not really > that convinced that removing really buys us that much code > simplification. It does buy us some reduction in number of variants (e.g. write_begin, write_end, writepage), we also wouldn't have to care about journalled data during invalidatepage() or releasepage() calls. > That being siad, it is true that data=journalled isn't necessarily > faster. For heavy disk-bound workloads, it can be slower. So I can > imagine adding some documentation that warns people not to use > data=journal unless they really know what they are doing, but at least > personally, I'm a bit reluctant to dispense with a bug report like > this by saying, "oh, that feature should be deprecated". No, I didn't want to dispense the bug report - we should definitely fix the bug. I just remarked that data=journal is currently not well tested and thus using it in production has its problems. Honza -- Jan Kara <jack@xxxxxxx> SUSE Labs, CR -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
