On Wed, 7 Sep 2011, Yehuda Sadeh 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>
Small fix below:
> ---
> qemu-img.c | 28 +++++++++++++++++++++++-----
> 1 files changed, 23 insertions(+), 5 deletions(-)
>
> diff --git a/qemu-img.c b/qemu-img.c
> index b205e98..0552746 100644
> --- a/qemu-img.c
> +++ b/qemu-img.c
> @@ -622,6 +622,17 @@ 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 void img_write_cb(void *opaque, int ret)
> +{
> + QEMUIOVector *qiov = (QEMUIOVector *)opaque;
> + write_window -= qiov->iov->iov_len / 512;
> + qemu_iovec_destroy(qiov);
> + qemu_free(qiov);
> +}
>
> static int img_convert(int argc, char **argv)
> {
> @@ -980,6 +991,9 @@ 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.
> @@ -989,11 +1003,11 @@ static int img_convert(int argc, char **argv)
> already there is garbage, not 0s. */
> if (!has_zero_init || out_baseimg ||
> is_allocated_sectors(buf1, n, &n1)) {
> - ret = bdrv_write(out_bs, sector_num, buf1, n1);
> - if (ret < 0) {
> - error_report("error while writing");
> - goto out;
> - }
> + QEMUIOVector *qiov = qemu_mallocz(sizeof(QEMUIOVector));
> + qemu_iovec_init(qiov, 1);
> + qemu_iovec_add(qiov, (void *)buf1, n1 * 512);
> + bdrv_aio_writev(out_bs, sector_num, qiov, n1, img_write_cb, qiov);
> + write_window += n1;
> }
> sector_num += n1;
> n -= n1;
> @@ -1001,11 +1015,15 @@ 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();
> free_option_parameters(create_options);
> free_option_parameters(param);
> + bdrv_flush(out_bs);
> qemu_free(buf);
> if (out_bs) {
> bdrv_delete(out_bs);
The bdrv_flush() needs to go inside the if or else we get a null
dereference on error (e.g. from a bad image name).
sage
> --
> 1.7.5.1
>
>
>
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