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

[Juergen Gross]

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 <o...@aepfle.de>
---
  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;

+            size_t pages_sent;
+            size_t overhead_sent;

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>

      iov[3].iov_len = nr_pfns * sizeof(*rec_pfns);

+    ctx->save.pages_sent += nr_pages;

unsigned long p2m_size; struct precopy_stats stats; diff --git a/tools/libs/saverestore/save.c b/tools/libs/saverestore/save.c #include "common.h" @@ -238,6 +239,8 @@ static int write_batch(struct xc_sr_context *ctx) iovcnt = 4; + 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;
  }

+{
+    xc_interface *xch = ctx->xch;
+    struct timespec end = {}, diff = {};
+    size_t ms, MiB_sec = ctx->save.pages_sent * PAGE_SIZE;

+static void show_transfer_rate(struct xc_sr_context *ctx, struct timespec *start)

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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