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Re: [Qemu-devel] [v3 04/13] qemu-file: Add tow function will be used in
From: |
Dr. David Alan Gilbert |
Subject: |
Re: [Qemu-devel] [v3 04/13] qemu-file: Add tow function will be used in migration |
Date: |
Fri, 23 Jan 2015 13:31:18 +0000 |
User-agent: |
Mutt/1.5.23 (2014-03-12) |
* Liang Li (address@hidden) wrote:
> migrate_qemu_add_compression_data() compress the data
> and put it to QEMUFile. migrate_qemu_flush() put the
> data in the source QEMUFile to destination QEMUFile.
>
> The two function can help to do live migration.
Typo in the title 'tow->two' - but perhaps a better title
would be 'Add compression functions to QEMUFile'
> Signed-off-by: Liang Li <address@hidden>
> Signed-off-by: Yang Zhang <address@hidden>
> ---
> include/migration/qemu-file.h | 3 +++
> qemu-file.c | 32 ++++++++++++++++++++++++++++++++
> 2 files changed, 35 insertions(+)
>
> diff --git a/include/migration/qemu-file.h b/include/migration/qemu-file.h
> index 401676b..d70fb8d 100644
> --- a/include/migration/qemu-file.h
> +++ b/include/migration/qemu-file.h
> @@ -150,6 +150,9 @@ void qemu_put_be32(QEMUFile *f, unsigned int v);
> void qemu_put_be64(QEMUFile *f, uint64_t v);
> int qemu_peek_buffer(QEMUFile *f, uint8_t *buf, int size, size_t offset);
> int qemu_get_buffer(QEMUFile *f, uint8_t *buf, int size);
> +size_t migrate_qemu_add_compression_data(QEMUFile *f,
> + const uint8_t *p, size_t size, int level);
> +int migrate_qemu_flush(QEMUFile *f_des, QEMUFile *f_src);
> /*
> * Note that you can only peek continuous bytes from where the current
> pointer
> * is; you aren't guaranteed to be able to peak to +n bytes unless you've
> diff --git a/qemu-file.c b/qemu-file.c
> index f938e36..2668ad0 100644
> --- a/qemu-file.c
> +++ b/qemu-file.c
> @@ -21,6 +21,7 @@
> * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
> * THE SOFTWARE.
> */
> +#include <zlib.h>
> #include "qemu-common.h"
> #include "qemu/iov.h"
> #include "qemu/sockets.h"
> @@ -993,3 +994,34 @@ QEMUFile *qemu_bufopen(const char *mode, QEMUSizedBuffer
> *input)
> }
> return s->file;
> }
> +
> +/* compress size bytes of data start at p with specific compression
> + * leve and store the compressed data to the buffer of f.
> + */
> +
> +size_t migrate_qemu_add_compression_data(QEMUFile *f,
> + const uint8_t *p, size_t size, int level)
It's an odd name, QEMUFile is only used by migration anyway;
maybe qemufile_add_compression_data ?
> +{
> + size_t blen = IO_BUF_SIZE - f->buf_index - sizeof(int);
> +
> + if (compress2(f->buf + f->buf_index + sizeof(int), &blen, (Bytef *)p,
> + size, level) != Z_OK) {
> + error_report("Compress Failed!");
> + return 0;
> + }
What are the 'sizeof(int)'s for? It's unusual because we normally keep the
format of the stream the same even if one side was a 32bit qemu and the other
64bit.
How do you know that there is enough space for the compress - i.e. what
happens if f->buf_index is too high?
> + qemu_put_be32(f, blen);
> + f->buf_index += blen;
> + return blen + sizeof(int);
> +}
> +
> +int migrate_qemu_flush(QEMUFile *f_des, QEMUFile *f_src)
> +{
> + int len = 0;
> +
> + if (f_src->buf_index > 0) {
> + len = f_src->buf_index;
> + qemu_put_buffer(f_des, f_src->buf, f_src->buf_index);
> + f_src->buf_index = 0;
> + }
> + return len;
> +}
Can you explain a bit more here how you're using the src file; I think
you're using it as kind of a dummy buffer; but it needs to be documented
somewhere. Again I'm also not sure of the name of this function.
Dave
> --
> 1.8.3.1
>
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK
- Re: [Qemu-devel] [v3 04/13] qemu-file: Add tow function will be used in migration,
Dr. David Alan Gilbert <=