Re: [RFC PATCH v2 6/9] migration/multifd: Move pages accounting into multifd_send_zero_page_detect()

[Peter Xu <peterx@redhat.com>]

On Mon, Jul 22, 2024 at 02:59:11PM -0300, Fabiano Rosas wrote:
> All references to pages are being removed from the multifd worker
> threads in order to allow multifd to deal with different payload
> types.
> 
> multifd_send_zero_page_detect() is called by all multifd migration
> paths that deal with pages and is the last spot where zero pages and
> normal page amounts are adjusted. Move the pages accounting into that
> function.

True, but it's a bit hackish to update (especially, normal) page counters
in a zero page detect function.

I understand you want to move pages out of the thread function, that's
fair. How about put it in your new multifd_ram_fill_packet()?

> 
> Signed-off-by: Fabiano Rosas <farosas@suse.de>
> ---
>  migration/multifd-zero-page.c | 7 ++++++-
>  migration/multifd.c           | 2 --
>  2 files changed, 6 insertions(+), 3 deletions(-)
> 
> diff --git a/migration/multifd-zero-page.c b/migration/multifd-zero-page.c
> index efc0424f74..899e8864c6 100644
> --- a/migration/multifd-zero-page.c
> +++ b/migration/multifd-zero-page.c
> @@ -14,6 +14,7 @@
>  #include "qemu/cutils.h"
>  #include "exec/ramblock.h"
>  #include "migration.h"
> +#include "migration-stats.h"
>  #include "multifd.h"
>  #include "options.h"
>  #include "ram.h"
> @@ -53,7 +54,7 @@ void multifd_send_zero_page_detect(MultiFDSendParams *p)
>  
>      if (!multifd_zero_page_enabled()) {
>          pages->normal_num = pages->num;
> -        return;
> +        goto out;
>      }
>  
>      /*
> @@ -74,6 +75,10 @@ void multifd_send_zero_page_detect(MultiFDSendParams *p)
>      }
>  
>      pages->normal_num = i;
> +
> +out:
> +    stat64_add(&mig_stats.normal_pages, pages->normal_num);
> +    stat64_add(&mig_stats.zero_pages, pages->num - pages->normal_num);
>  }
>  
>  void multifd_recv_zero_page_process(MultiFDRecvParams *p)
> diff --git a/migration/multifd.c b/migration/multifd.c
> index f64b053e44..fcdb12e04f 100644
> --- a/migration/multifd.c
> +++ b/migration/multifd.c
> @@ -972,8 +972,6 @@ static void *multifd_send_thread(void *opaque)
>  
>              stat64_add(&mig_stats.multifd_bytes,
>                         p->next_packet_size + p->packet_len);
> -            stat64_add(&mig_stats.normal_pages, pages->normal_num);
> -            stat64_add(&mig_stats.zero_pages, pages->num - pages->normal_num);
>  
>              multifd_pages_reset(pages);
>              p->next_packet_size = 0;
> -- 
> 2.35.3
> 

-- 
Peter Xu