From: Dave Barach <dave@barachs.net>
Date: Tue, 4 Feb 2020 21:10:17 +0000 (-0500)
Subject: vppinfra: deal with 0 return from os_cpu_clock_frequency()
X-Git-Tag: v20.09-rc0~661
X-Git-Url: https://gerrit.fd.io/r/gitweb?p=vpp.git;a=commitdiff_plain;h=51cabf2a1486e8b4aa6756184d6e2ba0efc78b8a

vppinfra: deal with 0 return from os_cpu_clock_frequency()

Sporadic reports of os_cpu_clock_frequency() returning 0.0 in highly
parallel container environments.

To avoid immediate division by zero:
  Step 1: try estimate_clock_frequency(1e-3).
  Step 2: give up. Pretend we have a 2gHz clock.

Type: fix

Signed-off-by: Dave Barach <dave@barachs.net>
Change-Id: I19d0fe5259b757ab778599c7026ce485153b43fa
---

diff --git a/src/vppinfra/time.c b/src/vppinfra/time.c
index 3b3acfa3d1b..27758dc7534 100644
--- a/src/vppinfra/time.c
+++ b/src/vppinfra/time.c
@@ -208,6 +208,22 @@ clib_time_init (clib_time_t * c)
 {
   clib_memset (c, 0, sizeof (c[0]));
   c->clocks_per_second = os_cpu_clock_frequency ();
+  /*
+   * Sporadic reports of os_cpu_clock_frequency() returning 0.0
+   * in highly parallel container environments.
+   * To avoid immediate division by zero:
+   *   Step 1: try estimate_clock_frequency().
+   *   Step 2: give up. Pretend we have a 2gHz clock.
+   */
+  if (PREDICT_FALSE (c->clocks_per_second == 0.0))
+    {
+      c->clocks_per_second = estimate_clock_frequency (1e-3);
+      if (c->clocks_per_second == 0.0)
+	{
+	  clib_warning ("os_cpu_clock_frequency() returned 0.0, use 2e9...");
+	  c->clocks_per_second = 2e9;
+	}
+    }
   c->seconds_per_clock = 1 / c->clocks_per_second;
   c->log2_clocks_per_second = min_log2_u64 ((u64) c->clocks_per_second);