blob: e336ba5a2cea5e3a278cf7abdf7f29665afc2145 (
plain) (
blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
|
#ifndef CPU_ID_INL_H_
#error "Direct inclusion of this file is not allowed, include cpu_id.h"
// For the sake of sane code completion.
#include "cpu_id.h"
#endif
#undef CPU_ID_INL_H_
#ifdef __linux__
#include <library/cpp/yt/rseq/rseq.h>
#endif
#include <util/system/compiler.h>
namespace NYT {
////////////////////////////////////////////////////////////////////////////////
namespace NDetail {
int GetCurrentCpuIdSlow();
} // namespace NDetail
Y_FORCE_INLINE int GetCurrentCpuId()
{
#ifdef YT_RSEQ_AVAILABLE
// Branch-free read of the rseq cpu_id: the offset always points at a readable
// field. A data-dependent branch on the offset here would defeat load pipelining.
auto cpuId = NRseq::ReadField<int>(NRseq::CpuIdFieldOffset);
// Negative means this thread is not registered yet or rseq is unavailable.
if (cpuId < 0) [[unlikely]] {
return NDetail::GetCurrentCpuIdSlow();
}
return cpuId;
#else
return NDetail::GetCurrentCpuIdSlow();
#endif
}
////////////////////////////////////////////////////////////////////////////////
} // namespace NYT
|
