From fc8408b601e271ed7da5017827cc2e99d816ada9 Mon Sep 17 00:00:00 2001
From: Dominic Kempf <dominic.kempf@iwr.uni-heidelberg.de>
Date: Thu, 31 Aug 2017 17:01:44 +0200
Subject: [PATCH] Provide TSC frequency regardless of dmesg availability
---
dune/perftool/common/tsc.cc | 40 +++++++++++++++++++++++++++++++++++--
dune/perftool/common/tsc.hh | 4 ++++
2 files changed, 42 insertions(+), 2 deletions(-)
diff --git a/dune/perftool/common/tsc.cc b/dune/perftool/common/tsc.cc
index 3459b95f..999eee11 100644
--- a/dune/perftool/common/tsc.cc
+++ b/dune/perftool/common/tsc.cc
@@ -23,7 +23,7 @@ namespace Dune {
#if __linux__
- TSC::Counter get_tsc_frequency()
+ TSC::Counter get_tsc_frequency_from_dmesg()
{
int pipe_fds[2];
if (pipe(pipe_fds) < 0)
@@ -99,7 +99,7 @@ namespace Dune {
DUNE_THROW(TSCError,"Child process failed with return status " << WEXITSTATUS(status));
if (result < 0)
- DUNE_THROW(TSCError,"Could not find TSC frequency information in kernel log");
+ DUNE_THROW(TSCNotInKernelLog,"Could not find TSC frequency information in kernel log");
}
@@ -109,6 +109,42 @@ namespace Dune {
}
+ TSC::Counter get_tsc_frequency_from_cpuinfo()
+ {
+ double result = -1.0;
+ try {
+ auto cpuinfo = std::ifstream("/proc/cpuinfo");
+ auto re = std::regex("bogomips\\s:\\s(\\d+\\.\\d+)$");
+
+ using std::getline;
+ for (std::string line ; getline(cpuinfo,line) ; )
+ {
+ if (auto match = std::smatch() ; std::regex_match(line,match,re))
+ {
+ result = 5e5 * std::stod(match[1].str());
+ break;
+ }
+ }
+ }
+ catch(std::exception& e) {
+ DUNE_THROW(TSCError,"error getting TSC frequency from /proc/cpuinfo: " << e.what());
+ }
+
+ if (result < 0)
+ DUNE_THROW(TSCError,"could not find bogomips value in /proc/cpuinfo");
+
+ return result;
+ }
+
+ TSC::Counter get_tsc_frequency()
+ {
+ try {
+ return get_tsc_frequency_from_dmesg();
+ }
+ catch (TSCNotInKernelLog&) {
+ return get_tsc_frequency_from_cpuinfo();
+ }
+ }
#elif __APPLE__
diff --git a/dune/perftool/common/tsc.hh b/dune/perftool/common/tsc.hh
index 207ec54e..c0027222 100644
--- a/dune/perftool/common/tsc.hh
+++ b/dune/perftool/common/tsc.hh
@@ -11,6 +11,10 @@ namespace Dune {
: public Exception
{};
+ class TSCNotInKernelLog
+ : public TSCError
+ {};
+
class TSC
{
--
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