45 static void do_time_measurements(volatile jlong& time_base,
46 volatile jlong& time_fast,
47 volatile jlong& time_base_elapsed,
48 volatile jlong& time_fast_elapsed) {
49 static const unsigned int FT_SLEEP_MILLISECS = 1;
50 const unsigned int loopcount = 3;
51
52 volatile jlong start = 0;
53 volatile jlong fstart = 0;
54 volatile jlong end = 0;
55 volatile jlong fend = 0;
56
57 // Figure out the difference between rdtsc and os provided timer.
58 // base algorithm adopted from JRockit.
59 for (unsigned int times = 0; times < loopcount; times++) {
60 start = os::elapsed_counter();
61 OrderAccess::fence();
62 fstart = os::rdtsc();
63
64 // use sleep to prevent compiler from optimizing
65 os::sleep(JavaThread::current(), FT_SLEEP_MILLISECS);
66
67 end = os::elapsed_counter();
68 OrderAccess::fence();
69 fend = os::rdtsc();
70
71 time_base += end - start;
72 time_fast += fend - fstart;
73
74 // basis for calculating the os tick start
75 // to fast time tick start offset
76 time_base_elapsed += end;
77 time_fast_elapsed += (fend - _epoch);
78 }
79
80 time_base /= loopcount;
81 time_fast /= loopcount;
82 time_base_elapsed /= loopcount;
83 time_fast_elapsed /= loopcount;
84 }
85
|
45 static void do_time_measurements(volatile jlong& time_base,
46 volatile jlong& time_fast,
47 volatile jlong& time_base_elapsed,
48 volatile jlong& time_fast_elapsed) {
49 static const unsigned int FT_SLEEP_MILLISECS = 1;
50 const unsigned int loopcount = 3;
51
52 volatile jlong start = 0;
53 volatile jlong fstart = 0;
54 volatile jlong end = 0;
55 volatile jlong fend = 0;
56
57 // Figure out the difference between rdtsc and os provided timer.
58 // base algorithm adopted from JRockit.
59 for (unsigned int times = 0; times < loopcount; times++) {
60 start = os::elapsed_counter();
61 OrderAccess::fence();
62 fstart = os::rdtsc();
63
64 // use sleep to prevent compiler from optimizing
65 JavaThread::current()->sleep(FT_SLEEP_MILLISECS);
66
67 end = os::elapsed_counter();
68 OrderAccess::fence();
69 fend = os::rdtsc();
70
71 time_base += end - start;
72 time_fast += fend - fstart;
73
74 // basis for calculating the os tick start
75 // to fast time tick start offset
76 time_base_elapsed += end;
77 time_fast_elapsed += (fend - _epoch);
78 }
79
80 time_base /= loopcount;
81 time_fast /= loopcount;
82 time_base_elapsed /= loopcount;
83 time_fast_elapsed /= loopcount;
84 }
85
|