[PATCH v20210616 10/36] tools: show migration transfer rate in send_dirty_pages

[Olaf Hering <olaf@xxxxxxxxx>]

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>

v02:
- rearrange MiB_sec calculation (jgross)
---
 tools/libs/saverestore/common.h |  2 ++
 tools/libs/saverestore/save.c   | 46 +++++++++++++++++++++++++++++++++
 2 files changed, 48 insertions(+)

diff --git a/tools/libs/saverestore/common.h b/tools/libs/saverestore/common.h
index 08bbe902b9..d61569e1a6 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 12598bd4e2..f8fbe7a742 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 +360,42 @@ 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;
+
+    if (!ctx->save.pages_sent)
+        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));
+    ms += (diff.tv_sec * 1000U);
+    if (!ms)
+        ms = 1;
+
+    MiB_sec = (ctx->save.pages_sent * PAGE_SIZE * 1000U) / ms / (1024U*1024U);
+
+    errno = 0;
+    IPRINTF("%s: %zu bytes + %zu pages in %ld.%09ld sec, %zu MiB/sec", 
__func__,
+            ctx->save.overhead_sent, ctx->save.pages_sent,
+            diff.tv_sec, diff.tv_nsec, MiB_sec);
+}
+
 /*
  * Send a subset of pages in the guests p2m, according to the dirty bitmap.
  * Used for each subsequent iteration of the live migration loop.
@@ -370,9 +409,15 @@ static int send_dirty_pages(struct xc_sr_context *ctx,
     xen_pfn_t p;
     unsigned long written;
     int rc;
+    struct timespec start = {};
     DECLARE_HYPERCALL_BUFFER_SHADOW(unsigned long, dirty_bitmap,
                                     &ctx->save.dirty_bitmap_hbuf);
 
+    ctx->save.pages_sent = 0;
+    ctx->save.overhead_sent = 0;
+    if ( clock_gettime(CLOCK_MONOTONIC, &start) )
+        PERROR("clock_gettime");
+
     for ( p = 0, written = 0; p < ctx->save.p2m_size; ++p )
     {
         if ( !test_bit(p, dirty_bitmap) )
@@ -396,6 +441,7 @@ static int send_dirty_pages(struct xc_sr_context *ctx,
     if ( written > entries )
         DPRINTF("Bitmap contained more entries than expected...");
 
+    show_transfer_rate(ctx, &start);
     xc_report_progress_step(xch, entries, entries);
 
     return ctx->save.ops.check_vm_state(ctx);