Re: [Qemu-devel] [PATCH v3 8/8] multifd: rest of zlib compression

[Dr. David Alan Gilbert]

* Juan Quintela (address@hidden) wrote:
> This is still a work in progress, but get everything sent as expected
> and it is faster than the code that is already there.
> 
> Signed-off-by: Juan Quintela <address@hidden>
> ---
>  migration/ram.c | 106 +++++++++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 104 insertions(+), 2 deletions(-)
> 
> diff --git a/migration/ram.c b/migration/ram.c
> index fdb5bf07a5..efbb253c1a 100644
> --- a/migration/ram.c
> +++ b/migration/ram.c
> @@ -747,6 +747,100 @@ MultifdMethods multifd_none_ops = {
>      .recv_pages = none_recv_pages
>  };
>  
> +/* Multifd zlib compression */
> +

Comment the return value?

> +static int zlib_send_prepare(MultiFDSendParams *p, uint32_t used)
> +{
> +    struct iovec *iov = p->pages->iov;
> +    z_stream *zs = &p->zs;
> +    uint32_t out_size = 0;
> +    int ret;
> +    int i;

uint32_t to match 'used' ?

> +    for (i = 0; i < used; i++) {
> +        uint32_t available = p->zbuff_len - out_size;
> +        int flush = Z_NO_FLUSH;
> +
> +        if (i == used  - 1) {
> +            flush = Z_SYNC_FLUSH;
> +        }
> +
> +        zs->avail_in = iov[i].iov_len;
> +        zs->next_in = iov[i].iov_base;
> +
> +        zs->avail_out = available;
> +        zs->next_out = p->zbuff + out_size;
> +
> +        ret = deflate(zs, flush);
> +        if (ret != Z_OK) {
> +            printf("problem with deflate? %d\n", ret);

If it's an error it should probably be at least an fprintf(stderr or
err_ something.

Should this also check that the avail_in/next_in has consumed the whole
of the input?

> +            qemu_mutex_unlock(&p->mutex);

Can you explain and/or comment whyit's unlocked here in the error path?

> +            return -1;
> +        }
> +        out_size += available - zs->avail_out;
> +    }
> +    p->next_packet_size = out_size;

Some traces_ wouldn't hurt.

> +    return 0;
> +}
> +
> +static int zlib_send_write(MultiFDSendParams *p, uint32_t used, Error **perr)
> +{
> +    return qio_channel_write_all(p->c, (void *)p->zbuff, p->next_packet_size,
> +                                 perr);
> +}
> +
> +static int zlib_recv_pages(MultiFDRecvParams *p, uint32_t used, Error **perr)
> +{
> +    uint32_t in_size = p->next_packet_size;
> +    uint32_t out_size = 0;
> +    uint32_t expected_size = used * qemu_target_page_size();
> +    z_stream *zs = &p->zs;
> +    int ret;
> +    int i;
> +
> +    ret = qio_channel_read_all(p->c, (void *)p->zbuff, in_size, perr);
> +
> +    if (ret != 0) {
> +        return ret;
> +    }
> +
> +    zs->avail_in = in_size;
> +    zs->next_in = p->zbuff;
> +
> +    for (i = 0; i < used; i++) {
> +        struct iovec *iov = &p->pages->iov[i];
> +        int flush = Z_NO_FLUSH;
> +
> +        if (i == used  - 1) {
> +            flush = Z_SYNC_FLUSH;
> +        }
> +
> +        zs->avail_out = iov->iov_len;
> +        zs->next_out = iov->iov_base;
> +
> +        ret = inflate(zs, flush);
> +        if (ret != Z_OK) {
> +            printf("%d: problem with inflate? %d\n", p->id, ret);
> +            qemu_mutex_unlock(&p->mutex);
> +            return ret;
> +        }
> +        out_size += iov->iov_len;
> +    }
> +    if (out_size != expected_size) {
> +        printf("out size %d expected size %d\n",
> +               out_size, expected_size);
> +        return -1;
> +    }
> +    return 0;
> +}
> +
> +MultifdMethods multifd_zlib_ops = {
> +    .send_prepare = zlib_send_prepare,
> +    .send_write = zlib_send_write,
> +    .recv_pages = zlib_recv_pages
> +};
> +
>  static int multifd_send_initial_packet(MultiFDSendParams *p, Error **errp)
>  {
>      MultiFDInit_t msg;
> @@ -1145,7 +1239,11 @@ static void *multifd_send_thread(void *opaque)
>      /* initial packet */
>      p->num_packets = 1;
>  
> -    multifd_send_state->ops = &multifd_none_ops;
> +    if (migrate_use_multifd_zlib()) {
> +        multifd_send_state->ops = &multifd_zlib_ops;
> +    } else {
> +        multifd_send_state->ops = &multifd_none_ops;
> +    }
>  
>      while (true) {
>          qemu_sem_wait(&p->sem);
> @@ -1399,7 +1497,11 @@ static void *multifd_recv_thread(void *opaque)
>      trace_multifd_recv_thread_start(p->id);
>      rcu_register_thread();
>  
> -    multifd_recv_state->ops = &multifd_none_ops;
> +    if (migrate_use_multifd_zlib()) {
> +        multifd_recv_state->ops = &multifd_zlib_ops;
> +    } else {
> +        multifd_recv_state->ops = &multifd_none_ops;
> +    }
>      while (true) {
>          uint32_t used;
>          uint32_t flags;
> -- 
> 2.21.0
> 
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK