On Sat, Jan 26, 2013 at 5:28 PM, Jens Axboe <axboe@xxxxxxxxx> wrote: > On Fri, Jan 25 2013, Stefan Hajnoczi wrote: >> Is there a way to flush the disk write cache when O_DIRECT is in use? >> >> It seems that direct=1 causes the fsync setting to be ignored. Asias >> writes: >> >> > The O_DIRECT do affect the flush behaviour. e.g >> > >> > guest$ fio --fsync=100 --direct=1 >> > No virtio_blk_handle_flush is observed on host side every 100 IOs >> > >> > guest$ fio --fsync=100 --direct=0 >> > virtio_blk_handle_flush is observed on host side every 100 IOs >> >> Am I missing a reason for this behavior? To me it seems weird since you >> could already use --fsync=0 --direct=1 if you want to guarantee that >> fsync is not called. I don't see a need to override the fsync setting. > > You are right, fio should not be double guessing options like that. If > you ask for fsync, you should get fsync. > > Does the below work for you? Yes, thanks! Tested-by: Stefan Hajnoczi <stefanha@xxxxxxxxxx> -- To unsubscribe from this list: send the line "unsubscribe fio" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
