Re: [PATCH v20210601 08/38] tools: show migration transfer rate in send_dirty_pages

[Juergen Gross <jgross@xxxxxxxx>]

On 01.06.21 18:10, Olaf Hering wrote:
> Show how fast domU pages are transferred in each iteration.
>
> The relevant data is how fast the pfns travel, not so much how much
> protocol overhead exists. So the reported MiB/sec is just for pfns.
>
> Signed-off-by: Olaf Hering <olaf@xxxxxxxxx>
> ---
>   tools/libs/saverestore/common.h |  2 ++
>   tools/libs/saverestore/save.c   | 47 +++++++++++++++++++++++++++++++++
>   2 files changed, 49 insertions(+)
>
> diff --git a/tools/libs/saverestore/common.h b/tools/libs/saverestore/common.h
> index 50a8479d39..f5fe23caad 100644
> --- a/tools/libs/saverestore/common.h
> +++ b/tools/libs/saverestore/common.h
> @@ -250,6 +250,8 @@ struct xc_sr_context
>               bool debug;
>   
>               unsigned long p2m_size;
> +            size_t pages_sent;
> +            size_t overhead_sent;
>   
>               struct precopy_stats stats;
>   
> diff --git a/tools/libs/saverestore/save.c b/tools/libs/saverestore/save.c
> index bcff2d28f5..760ca04a84 100644
> --- a/tools/libs/saverestore/save.c
> +++ b/tools/libs/saverestore/save.c
> @@ -1,5 +1,6 @@
>   #include <assert.h>
>   #include <arpa/inet.h>
> +#include <time.h>
>   
>   #include "common.h"
>   
> @@ -238,6 +239,8 @@ static int write_batch(struct xc_sr_context *ctx)
>       iov[3].iov_len = nr_pfns * sizeof(*rec_pfns);
>   
>       iovcnt = 4;
> +    ctx->save.pages_sent += nr_pages;
> +    ctx->save.overhead_sent += sizeof(rec) + sizeof(hdr) + nr_pfns * 
sizeof(*rec_pfns);
>   
>       if ( nr_pages )
>       {
> @@ -357,6 +360,43 @@ static int suspend_domain(struct xc_sr_context *ctx)
>       return 0;
>   }
>   
> +static void show_transfer_rate(struct xc_sr_context *ctx, struct timespec *start)
> +{
> +    xc_interface *xch = ctx->xch;
> +    struct timespec end = {}, diff = {};
> +    size_t ms, MiB_sec = ctx->save.pages_sent * PAGE_SIZE;
I'd rather not initialize MiB_sec here ...

> +
> +    if (!MiB_sec)
... and test for ctx->save.pages_sent to be non-zero here.

> +        return;
> +
> +    if ( clock_gettime(CLOCK_MONOTONIC, &end) )
> +        PERROR("clock_gettime");
> +
> +    if ( (end.tv_nsec - start->tv_nsec) < 0 )
> +    {
> +        diff.tv_sec = end.tv_sec - start->tv_sec - 1;
> +        diff.tv_nsec = end.tv_nsec - start->tv_nsec + (1000U*1000U*1000U);
> +    }
> +    else
> +    {
> +        diff.tv_sec = end.tv_sec - start->tv_sec;
> +        diff.tv_nsec = end.tv_nsec - start->tv_nsec;
> +    }
> +
> +    ms = (diff.tv_nsec / (1000U*1000U));
> +    if (!ms)
> +        ms = 1;
I'd move this ...

> +    ms += (diff.tv_sec * 1000U);
... below this.

> +
> +    MiB_sec *= 1000U;
> +    MiB_sec /= ms;
> +    MiB_sec /= 1024U*1024U;
Avoid MiB_sec holding bytes per second for some time and use:

MiB_sec = ((ctx->save.pages_sent * PAGE_SIZE * 1000) / ms) /
          (1024U * 1024U);


Juergen

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