On Sun, May 22, 2011 at 03:21:22PM +0900, Jun OKAJIMA wrote: > I assign VirtualBox disk image (.vdi) files on a USB stick. > I have found that it is painfully slow. > The reason is easy. > VirtualBox flushes write caches very often. > Even you make dirty_writeback_centisecs and alike very long, the result is same. > > Then, how it flushes often? > do sync(2) often? No. > >From an output of strace, it is no. > No sync, no fsync, no fdatasync.... > and no O_DIRECT and no O_SYNC .... > How VirtualBox flushes so often? Why not ask the virtualbox developers, they would know what they did in their driver, it's not something that we know anything about here. sorry, greg k-h -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
