diff options
| -rw-r--r-- | mysys/my_cpu.c | 11 |
1 files changed, 8 insertions, 3 deletions
diff --git a/mysys/my_cpu.c b/mysys/my_cpu.c index 9434bceac41..3b0ef08a326 100644 --- a/mysys/my_cpu.c +++ b/mysys/my_cpu.c @@ -72,8 +72,13 @@ internally invokes rdtsc. */ that. In some AMD processors, the PAUSE instruction could take 40 or 50 cycles. Let us use a shorter delay multiplier for them as well. - The 1/10 scaling factor (200/20) was derived experimentally by - Mikhail Sinyavin from Intel. + The 1/2 scaling factor (200/100) was derived experimentally by + Steve Shaw from Intel and Sergey Vojtovich from MariaDB Foundation. + In an earlier experiment on MySQL code base, a 1/10 scaling factor + (200/20) seemed to work best. + + The basic idea of the detection algorithm (run 16 PAUSE instructions + between RDTSC) was suggested by Mikhail Sinyavin from Intel. */ void my_cpu_init(void) { @@ -84,6 +89,6 @@ void my_cpu_init(void) PAUSE16; t2= my_timer_cycles(); if (t2 - t1 > 30 * 16 && t1 - t0 > 30 * 16) - my_cpu_relax_multiplier= 20; + my_cpu_relax_multiplier= 100; } #endif |