On Wed, Dec 05, 2012 at 05:42:51PM +0000, Thorn Roby wrote: > My previous reply was incorrect in one point - the data is never copied from > the transaction log into the sparse datafiles, instead the application writes > the same data independently to both locations. > Also, I failed to mention that the files are memmapped, and it's possible > that the write operations attempt to use DIRECT_IO, which I believe is > disabled by btrfs with compression - is it possible that an attempt to use > DIRECT_IO or memmapped files would prevent compression? >
Actually, writting with DIRECT_IO will fall back to buffer write for safety, and mmap files just dirty pages, should be same with buffer write, so it might be other reasons. thanks, liubo -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
