Re: [PATCH 5/7] migration/multifd: Add UADK based compression and decompression

[Fabiano Rosas <farosas@suse.de>]

Shameer Kolothum via <qemu-devel@nongnu.org> writes:

> Uses UADK wd_do_comp_sync() API to (de)compress a normal page using
> hardware accelerator.
>
> Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>

A couple of comments below.

Reviewed-by: Fabiano Rosas <farosas@suse.de>

> ---
>  migration/multifd-uadk.c | 132 ++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 130 insertions(+), 2 deletions(-)
>
> diff --git a/migration/multifd-uadk.c b/migration/multifd-uadk.c
> index 3172e4d5ca..3329819bd4 100644
> --- a/migration/multifd-uadk.c
> +++ b/migration/multifd-uadk.c
> @@ -13,6 +13,7 @@
>  #include "qemu/osdep.h"
>  #include "qemu/module.h"
>  #include "qapi/error.h"
> +#include "exec/ramblock.h"
>  #include "migration.h"
>  #include "multifd.h"
>  #include "options.h"
> @@ -140,6 +141,15 @@ static void multifd_uadk_send_cleanup(MultiFDSendParams *p, Error **errp)
>      p->compress_data = NULL;
>  }
>  
> +static inline void prepare_next_iov(MultiFDSendParams *p, void *base,
> +                                    uint32_t len)
> +{
> +    p->iov[p->iovs_num].iov_base = (uint8_t *)base;
> +    p->iov[p->iovs_num].iov_len = len;
> +    p->next_packet_size += len;
> +    p->iovs_num++;
> +}
> +
>  /**
>   * multifd_uadk_send_prepare: prepare data to be able to send
>   *
> @@ -153,7 +163,56 @@ static void multifd_uadk_send_cleanup(MultiFDSendParams *p, Error **errp)
>   */
>  static int multifd_uadk_send_prepare(MultiFDSendParams *p, Error **errp)
>  {
> -    return -1;
> +    struct wd_data *uadk_data = p->compress_data;
> +    uint32_t hdr_size;
> +    uint8_t *buf = uadk_data->buf;
> +    int ret = 0;
> +
> +    if (!multifd_send_prepare_common(p)) {
> +        goto out;
> +    }
> +
> +    hdr_size = p->pages->normal_num * sizeof(uint32_t);
> +    /* prepare the header that stores the lengths of all compressed data */
> +    prepare_next_iov(p, uadk_data->buf_hdr, hdr_size);
> +
> +    for (int i = 0; i < p->pages->normal_num; i++) {
> +        struct wd_comp_req creq = {
> +            .op_type = WD_DIR_COMPRESS,
> +            .src     = p->pages->block->host + p->pages->offset[i],
> +            .src_len = p->page_size,
> +            .dst     = buf,
> +            /* Set dst_len to double the src to take care of -ve compression */

What's -ve compression?

> +            .dst_len = p->page_size * 2,
> +        };
> +
> +        ret = wd_do_comp_sync(uadk_data->handle, &creq);
> +        if (ret || creq.status) {
> +            error_setg(errp, "multifd %u: failed wd_do_comp_sync, ret %d status %d",
> +                       p->id, ret, creq.status);
> +            return -1;
> +        }
> +        if (creq.dst_len < p->page_size) {
> +            uadk_data->buf_hdr[i] = cpu_to_be32(creq.dst_len);
> +            prepare_next_iov(p, buf, creq.dst_len);
> +            buf += creq.dst_len;
> +        } else {
> +            /*
> +             * Send raw data if compressed out >= page_size. We might be better
> +             * off sending raw data if output is slightly less than page_size
> +             * as well because at the receive end we can skip the decompression.
> +             * But it is tricky to find the right number here.
> +             */
> +            uadk_data->buf_hdr[i] = cpu_to_be32(p->page_size);
> +            prepare_next_iov(p, p->pages->block->host + p->pages->offset[i],
> +                             p->page_size);
> +            buf += p->page_size;
> +        }
> +    }
> +out:
> +    p->flags |= MULTIFD_FLAG_UADK;
> +    multifd_send_fill_packet(p);
> +    return 0;
>  }
>  
>  /**
> @@ -206,7 +265,76 @@ static void multifd_uadk_recv_cleanup(MultiFDRecvParams *p)
>   */
>  static int multifd_uadk_recv(MultiFDRecvParams *p, Error **errp)
>  {
> -    return -1;
> +    struct wd_data *uadk_data = p->compress_data;
> +    uint32_t in_size = p->next_packet_size;
> +    uint32_t flags = p->flags & MULTIFD_FLAG_COMPRESSION_MASK;
> +    uint32_t hdr_len = p->normal_num * sizeof(uint32_t);
> +    uint32_t data_len = 0;
> +    uint8_t *buf = uadk_data->buf;
> +    int ret = 0;
> +
> +    if (flags != MULTIFD_FLAG_UADK) {
> +        error_setg(errp, "multifd %u: flags received %x flags expected %x",
> +                   p->id, flags, MULTIFD_FLAG_ZLIB);
> +        return -1;
> +    }
> +
> +    multifd_recv_zero_page_process(p);
> +    if (!p->normal_num) {
> +        assert(in_size == 0);
> +        return 0;
> +    }
> +
> +    /* read compressed data lengths */
> +    assert(hdr_len < in_size);
> +    ret = qio_channel_read_all(p->c, (void *) uadk_data->buf_hdr,
> +                               hdr_len, errp);
> +    if (ret != 0) {
> +        return ret;
> +    }
> +
> +    for (int i = 0; i < p->normal_num; i++) {
> +        uadk_data->buf_hdr[i] = be32_to_cpu(uadk_data->buf_hdr[i]);
> +        data_len += uadk_data->buf_hdr[i];
> +        assert(uadk_data->buf_hdr[i] <= p->page_size);
> +    }
> +
> +    /* read compressed data */
> +    assert(in_size == hdr_len + data_len);
> +    ret = qio_channel_read_all(p->c, (void *)buf, data_len, errp);
> +    if (ret != 0) {
> +        return ret;
> +    }
> +
> +    for (int i = 0; i < p->normal_num; i++) {
> +        struct wd_comp_req creq = {
> +            .op_type = WD_DIR_DECOMPRESS,
> +            .src     = buf,
> +            .src_len = uadk_data->buf_hdr[i],
> +            .dst     = p->host + p->normal[i],
> +            .dst_len = p->page_size,
> +        };
> +
> +        if (uadk_data->buf_hdr[i] == p->page_size) {
> +            memcpy(p->host + p->normal[i], buf, p->page_size);
> +            buf += p->page_size;
> +            continue;
> +        }
> +
> +        ret = wd_do_comp_sync(uadk_data->handle, &creq);
> +        if (ret || creq.status) {
> +            error_setg(errp, "multifd %u: failed wd_do_comp_sync, ret %d status %d",
> +                       p->id, ret, creq.status);

It would be nice to be able to tell compression from decompression in
these error messages.

> +            return -1;
> +        }
> +        if (creq.dst_len != p->page_size) {
> +            error_setg(errp, "multifd %u: decompressed length error", p->id);
> +            return -1;
> +        }
> +        buf += uadk_data->buf_hdr[i];
> +     }
> +
> +    return 0;
>  }
>  
>  static MultiFDMethods multifd_uadk_ops = {