Note that I assumed qemu-img runs in a single context (like qemu), and
there are no concurrency issues. If that's not the case, the callback,
error handling need to be fixed.
Yehuda
On Mon, Sep 12, 2011 at 7:26 AM, Yehuda Sadeh <yehuda@xxxxxxxxxxxxxxx> wrote:
> In order to improve image conversion process, instead of synchronously
> writing the destingation image, we keep a window of async writes.
>
> Signed-off-by: Yehuda Sadeh <yehuda@xxxxxxxxxxxxxxx>
> ---
> qemu-img.c | 47 +++++++++++++++++++++++++++++++++++++++++++----
> 1 files changed, 43 insertions(+), 4 deletions(-)
>
> diff --git a/qemu-img.c b/qemu-img.c
> index 6a39731..a45f5f2 100644
> --- a/qemu-img.c
> +++ b/qemu-img.c
> @@ -646,6 +646,29 @@ static int compare_sectors(const uint8_t *buf1, const uint8_t *buf2, int n,
> }
>
> #define IO_BUF_SIZE (2 * 1024 * 1024)
> +#define IO_WRITE_WINDOW_THRESHOLD (32 * 1024 * 1024)
> +
> +static int write_window = 0;
> +static int write_ret = 0;
> +
> +struct write_info {
> + int64_t sector;
> + QEMUIOVector qiov;
> +};
> +
> +static void img_write_cb(void *opaque, int ret)
> +{
> + struct write_info *wr = (struct write_info *)opaque;
> + QEMUIOVector *qiov = &wr->qiov;
> + if (ret < 0) {
> + error_report("error while writing sector %" PRId64
> + ": %s", wr->sector, strerror(-ret));
> + write_ret = ret;
> + }
> + write_window -= qiov->iov->iov_len / 512;
> + qemu_iovec_destroy(qiov);
> + g_free(wr);
> +}
>
> static int img_convert(int argc, char **argv)
> {
> @@ -1019,6 +1042,9 @@ static int img_convert(int argc, char **argv)
> should add a specific call to have the info to go faster */
> buf1 = buf;
> while (n > 0) {
> + while (write_window > IO_WRITE_WINDOW_THRESHOLD / 512) {
> + qemu_aio_wait();
> + }
> /* If the output image is being created as a copy on write image,
> copy all sectors even the ones containing only NUL bytes,
> because they may differ from the sectors in the base image.
> @@ -1028,12 +1054,21 @@ static int img_convert(int argc, char **argv)
> already there is garbage, not 0s. */
> if (!has_zero_init || out_baseimg ||
> is_allocated_sectors_min(buf1, n, &n1, min_sparse)) {
> - ret = bdrv_write(out_bs, sector_num, buf1, n1);
> - if (ret < 0) {
> - error_report("error while writing sector %" PRId64
> - ": %s", sector_num, strerror(-ret));
> + QEMUIOVector *qiov;
> + struct write_info *wr;
> + BlockDriverAIOCB *acb;
> + wr = g_malloc0(sizeof(struct write_info));
> + qiov = &wr->qiov;
> + qemu_iovec_init(qiov, 1);
> + qemu_iovec_add(qiov, (void *)buf1, n1 * 512);
> + wr->sector = sector_num;
> + acb = bdrv_aio_writev(out_bs, sector_num, qiov, n1, img_write_cb, wr);
> + if (!acb) {
> + g_free(wr);
> + error_report("I/O error while writing sector %" PRId64, sector_num);
> goto out;
> }
> + write_window += n1;
> }
> sector_num += n1;
> n -= n1;
> @@ -1041,6 +1076,9 @@ static int img_convert(int argc, char **argv)
> }
> qemu_progress_print(local_progress, 100);
> }
> + while (write_window > 0) {
> + qemu_aio_wait();
> + }
> }
> out:
> qemu_progress_end();
> @@ -1048,6 +1086,7 @@ out:
> free_option_parameters(param);
> qemu_vfree(buf);
> if (out_bs) {
> + bdrv_flush(out_bs);
> bdrv_delete(out_bs);
> }
> if (bs) {
> --
> 1.7.5.1
>
>
--
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
