summaryrefslogtreecommitdiffstats
path: root/src/vppinfra/time.c
diff options
context:
space:
mode:
Diffstat (limited to 'src/vppinfra/time.c')
-rw-r--r--src/vppinfra/time.c226
1 files changed, 226 insertions, 0 deletions
diff --git a/src/vppinfra/time.c b/src/vppinfra/time.c
new file mode 100644
index 00000000000..2bdb9da4b39
--- /dev/null
+++ b/src/vppinfra/time.c
@@ -0,0 +1,226 @@
+/*
+ * Copyright (c) 2015 Cisco and/or its affiliates.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+/*
+ Copyright (c) 2005 Eliot Dresselhaus
+
+ Permission is hereby granted, free of charge, to any person obtaining
+ a copy of this software and associated documentation files (the
+ "Software"), to deal in the Software without restriction, including
+ without limitation the rights to use, copy, modify, merge, publish,
+ distribute, sublicense, and/or sell copies of the Software, and to
+ permit persons to whom the Software is furnished to do so, subject to
+ the following conditions:
+
+ The above copyright notice and this permission notice shall be
+ included in all copies or substantial portions of the Software.
+
+ THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+ LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+ OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+*/
+
+#include <vppinfra/os.h>
+#include <vppinfra/time.h>
+#include <vppinfra/format.h>
+#include <vppinfra/cpu.h>
+
+#ifdef CLIB_UNIX
+
+#include <math.h>
+#include <sys/time.h>
+#include <fcntl.h>
+
+/* Not very accurate way of determining cpu clock frequency
+ for unix. Better to use /proc/cpuinfo on linux. */
+static f64
+estimate_clock_frequency (f64 sample_time)
+{
+ /* Round to nearest 100KHz. */
+ const f64 round_to_units = 100e5;
+
+ f64 time_now, time_start, time_limit, freq;
+ u64 ifreq, t[2];
+
+ time_start = time_now = unix_time_now ();
+ time_limit = time_now + sample_time;
+ t[0] = clib_cpu_time_now ();
+ while (time_now < time_limit)
+ time_now = unix_time_now ();
+ t[1] = clib_cpu_time_now ();
+
+ freq = (t[1] - t[0]) / (time_now - time_start);
+ ifreq = flt_round_nearest (freq / round_to_units);
+ freq = ifreq * round_to_units;
+
+ return freq;
+}
+
+/* Fetch cpu frequency via parseing /proc/cpuinfo.
+ Only works for Linux. */
+static f64
+clock_frequency_from_proc_filesystem (void)
+{
+ f64 cpu_freq = 1e9; /* better than 40... */
+ f64 ppc_timebase = 0; /* warnings be gone */
+ int fd;
+ unformat_input_t input;
+
+/* $$$$ aarch64 kernel doesn't report "cpu MHz" */
+#if defined(__aarch64__)
+ return 0.0;
+#endif
+
+ cpu_freq = 0;
+ fd = open ("/proc/cpuinfo", 0);
+ if (fd < 0)
+ return cpu_freq;
+
+ unformat_init_unix_file (&input, fd);
+
+ ppc_timebase = 0;
+ while (unformat_check_input (&input) != UNFORMAT_END_OF_INPUT)
+ {
+ if (unformat (&input, "cpu MHz : %f", &cpu_freq))
+ cpu_freq *= 1e6;
+ else if (unformat (&input, "timebase : %f", &ppc_timebase))
+ ;
+ else
+ unformat_skip_line (&input);
+ }
+
+ unformat_free (&input);
+
+ close (fd);
+
+ /* Override CPU frequency with time base for PPC. */
+ if (ppc_timebase != 0)
+ cpu_freq = ppc_timebase;
+
+ return cpu_freq;
+}
+
+/* Fetch cpu frequency via reading /sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_max_freq
+ Only works for Linux. */
+static f64
+clock_frequency_from_sys_filesystem (void)
+{
+ f64 cpu_freq;
+ int fd;
+ unformat_input_t input;
+
+ /* Time stamp always runs at max frequency. */
+ cpu_freq = 0;
+ fd = open ("/sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_max_freq", 0);
+ if (fd < 0)
+ goto done;
+
+ unformat_init_unix_file (&input, fd);
+ unformat (&input, "%f", &cpu_freq);
+ cpu_freq *= 1e3; /* measured in kHz */
+ unformat_free (&input);
+ close (fd);
+done:
+ return cpu_freq;
+}
+
+f64
+os_cpu_clock_frequency (void)
+{
+ f64 cpu_freq;
+
+ if (clib_cpu_supports_invariant_tsc ())
+ return estimate_clock_frequency (1e-3);
+
+ /* First try /sys version. */
+ cpu_freq = clock_frequency_from_sys_filesystem ();
+ if (cpu_freq != 0)
+ return cpu_freq;
+
+ /* Next try /proc version. */
+ cpu_freq = clock_frequency_from_proc_filesystem ();
+ if (cpu_freq != 0)
+ return cpu_freq;
+
+ /* If /proc/cpuinfo fails (e.g. not running on Linux) fall back to
+ gettimeofday based estimated clock frequency. */
+ return estimate_clock_frequency (1e-3);
+}
+
+#endif /* CLIB_UNIX */
+
+/* Initialize time. */
+void
+clib_time_init (clib_time_t * c)
+{
+ memset (c, 0, sizeof (c[0]));
+ c->clocks_per_second = os_cpu_clock_frequency ();
+ c->seconds_per_clock = 1 / c->clocks_per_second;
+ c->log2_clocks_per_second = min_log2_u64 ((u64) c->clocks_per_second);
+
+ /* Initially verify frequency every sec */
+ c->log2_clocks_per_frequency_verify = c->log2_clocks_per_second;
+
+ c->last_verify_reference_time = unix_time_now ();
+ c->last_cpu_time = clib_cpu_time_now ();
+ c->init_cpu_time = c->last_verify_cpu_time = c->last_cpu_time;
+}
+
+void
+clib_time_verify_frequency (clib_time_t * c)
+{
+ f64 now_reference = unix_time_now ();
+ f64 dtr = now_reference - c->last_verify_reference_time;
+ f64 dtr_max;
+ u64 dtc = c->last_cpu_time - c->last_verify_cpu_time;
+ f64 round_units = 100e5;
+
+ c->last_verify_cpu_time = c->last_cpu_time;
+ c->last_verify_reference_time = now_reference;
+
+ /*
+ * Is the reported reference interval non-positive,
+ * or off by a factor of two - or 8 seconds - whichever is larger?
+ * Someone reset the clock behind our back.
+ */
+ dtr_max = (f64) (2ULL << c->log2_clocks_per_frequency_verify) /
+ (f64) (1ULL << c->log2_clocks_per_second);
+ dtr_max = dtr_max > 8.0 ? dtr_max : 8.0;
+
+ if (dtr <= 0.0 || dtr > dtr_max)
+ {
+ c->log2_clocks_per_frequency_verify = c->log2_clocks_per_second;
+ return;
+ }
+
+ c->clocks_per_second =
+ flt_round_nearest ((f64) dtc / (dtr * round_units)) * round_units;
+ c->seconds_per_clock = 1 / c->clocks_per_second;
+
+ /* Double time between verifies; max at 64 secs ~ 1 minute. */
+ if (c->log2_clocks_per_frequency_verify < c->log2_clocks_per_second + 6)
+ c->log2_clocks_per_frequency_verify += 1;
+}
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */