Commit b2780118 authored by Thomas Gleixner's avatar Thomas Gleixner Committed by Peter Zijlstra
Browse files

x86: Inline TSC reads in timekeeping 



Avoid the overhead of the indirect call for a single instruction to read
the TSC.

Signed-off-by: default avatarThomas Gleixner <tglx@kernel.org>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260224163429.741886362@kernel.org
parent 2e27beeb

arch/x86/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -141,6 +141,7 @@ config X86 
	select ARCH_USE_SYM_ANNOTATIONS

	select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH

	select ARCH_WANT_DEFAULT_BPF_JIT	if X86_64

	select ARCH_WANTS_CLOCKSOURCE_READ_INLINE	if X86_64

	select ARCH_WANTS_DYNAMIC_TASK_STRUCT

	select ARCH_WANTS_NO_INSTR

	select ARCH_WANT_GENERAL_HUGETLB

arch/x86/include/asm/clock_inlined.h

0 → 100644
+14 −0
Original line number Diff line number Diff line 
/* SPDX-License-Identifier: GPL-2.0 */

#ifndef _ASM_X86_CLOCK_INLINED_H

#define _ASM_X86_CLOCK_INLINED_H



#include <asm/tsc.h>



struct clocksource;



static __always_inline u64 arch_inlined_clocksource_read(struct clocksource *cs)

{

	return (u64)rdtsc_ordered();

}



#endif

arch/x86/kernel/tsc.c

+1 −0
Original line number Diff line number Diff line
@@ -1201,6 +1201,7 @@ static struct clocksource clocksource_tsc = { 
	.mask			= CLOCKSOURCE_MASK(64),

	.flags			= CLOCK_SOURCE_IS_CONTINUOUS |

				  CLOCK_SOURCE_VALID_FOR_HRES |

				  CLOCK_SOURCE_CAN_INLINE_READ |

				  CLOCK_SOURCE_MUST_VERIFY |

				  CLOCK_SOURCE_VERIFY_PERCPU,

	.id			= CSID_X86_TSC,