On Wed, Sep 07, 2011 at 04:06:51PM -0700, Yehuda Sadeh wrote: > The following set of patches improve the qemu-img conversion process > performance. When using a higher latency backend, small writes have a > severe impact on the time it takes to do image conversion. > We switch to using async writes, and we avoid splitting writes due to > holes when the holes are small enough. > > Yehuda Sadeh (2): > qemu-img: async write to block device when converting image > qemu-img: don't skip writing small holes > > qemu-img.c | 34 +++++++++++++++++++++++++++------- > 1 files changed, 27 insertions(+), 7 deletions(-) > > -- > 2.7.5.1 This has nothing to do with the patch itself, but I've been curious about the existence of both a QEMU and a Linux kernel rbd block driver. The I/O latency with qemu-img has been an issue for rbd users. But they have the option of using the Linux kernel rbd block driver, where qemu-img can take advantage of the page cache instead of performing direct I/O. Does this mean you intend to support both QEMU block/rbd.c and Linux drivers/block/rbd.c? As a user I would go with the Linux kernel driver instead of the QEMU block driver because it offers page cache and host block device features. On the other hand a userspace driver is nice because it does not require privileges. Stefan -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
