RE: [PATCH v7 05/13] multifd: Count the number of bytes sent correctly

[Zhang, Chen]

> -----Original Message-----
> From: Qemu-devel <qemu-devel-
> bounces+chen.zhang=intel.com@nongnu.org> On Behalf Of Juan Quintela
> Sent: Tuesday, May 31, 2022 6:43 PM
> To: qemu-devel@nongnu.org
> Cc: Marcel Apfelbaum <marcel.apfelbaum@gmail.com>; Philippe Mathieu-
> Daudé <f4bug@amsat.org>; Yanan Wang <wangyanan55@huawei.com>; Dr.
> David Alan Gilbert <dgilbert@redhat.com>; Juan Quintela
> <quintela@redhat.com>; Eduardo Habkost <eduardo@habkost.net>; Peter
> Xu <peterx@redhat.com>; Leonardo Bras <leobras@redhat.com>
> Subject: [PATCH v7 05/13] multifd: Count the number of bytes sent correctly
> 
> Current code asumes that all pages are whole.  That is not true for example
> for compression already.  Fix it for creating a new field
> ->sent_bytes that includes it.
> 
> All ram_counters are used only from the migration thread, so we have two
> options:
> - put a mutex and fill everything when we sent it (not only ram_counters,
> also qemu_file->xfer_bytes).
> - Create a local variable that implements how much has been sent through
> each channel.  And when we push another packet, we "add" the previous
> stats.
> 
> I choose two due to less changes overall.  On the previous code we increase
> transferred and then we sent.  Current code goes the other way around.  It
> sents the data, and after the fact, it updates the counters.  Notice that each
> channel can have a maximum of half a megabyte of data without counting, so
> it is not very important.
> 
> Signed-off-by: Juan Quintela <quintela@redhat.com>
> ---
>  migration/multifd.h |  2 ++
>  migration/multifd.c | 14 ++++++--------
>  2 files changed, 8 insertions(+), 8 deletions(-)
> 
> diff --git a/migration/multifd.h b/migration/multifd.h index
> 71f49b4063..8a45dda58c 100644
> --- a/migration/multifd.h
> +++ b/migration/multifd.h
> @@ -102,6 +102,8 @@ typedef struct {
>      uint32_t flags;
>      /* global number of generated multifd packets */
>      uint64_t packet_num;
> +    /* How many bytes have we sent on the last packet */
> +    uint64_t sent_bytes;
>      /* thread has work to do */
>      int pending_job;
>      /* array of pages to sent.
> diff --git a/migration/multifd.c b/migration/multifd.c index
> 166246b9b7..eef47c274f 100644
> --- a/migration/multifd.c
> +++ b/migration/multifd.c
> @@ -394,7 +394,6 @@ static int multifd_send_pages(QEMUFile *f)
>      static int next_channel;
>      MultiFDSendParams *p = NULL; /* make happy gcc */
>      MultiFDPages_t *pages = multifd_send_state->pages;
> -    uint64_t transferred;
> 
>      if (qatomic_read(&multifd_send_state->exiting)) {
>          return -1;
> @@ -429,10 +428,10 @@ static int multifd_send_pages(QEMUFile *f)
>      p->packet_num = multifd_send_state->packet_num++;
>      multifd_send_state->pages = p->pages;
>      p->pages = pages;
> -    transferred = ((uint64_t) pages->num) * p->page_size + p->packet_len;
> -    qemu_file_update_transfer(f, transferred);
> -    ram_counters.multifd_bytes += transferred;
> -    ram_counters.transferred += transferred;
> +    ram_transferred_add(p->sent_bytes);
> +    ram_counters.multifd_bytes += p->sent_bytes;
> +    qemu_file_update_transfer(f, p->sent_bytes);
> +    p->sent_bytes = 0;
>      qemu_mutex_unlock(&p->mutex);
>      qemu_sem_post(&p->sem);
> 
> @@ -605,9 +604,6 @@ int multifd_send_sync_main(QEMUFile *f)
>          p->packet_num = multifd_send_state->packet_num++;
>          p->flags |= MULTIFD_FLAG_SYNC;
>          p->pending_job++;
> -        qemu_file_update_transfer(f, p->packet_len);
> -        ram_counters.multifd_bytes += p->packet_len;
> -        ram_counters.transferred += p->packet_len;
>          qemu_mutex_unlock(&p->mutex);
>          qemu_sem_post(&p->sem);
> 
> @@ -712,6 +708,8 @@ static void *multifd_send_thread(void *opaque)
>              }
> 
>              qemu_mutex_lock(&p->mutex);
> +            p->sent_bytes += p->packet_len;;

Typo here about ";;" ? 

Thanks
Chen

> +            p->sent_bytes += p->next_packet_size;
>              p->pending_job--;
>              qemu_mutex_unlock(&p->mutex);
> 
> --
> 2.35.3
>