From: Thomas Gleixner <tglx@kernel.org>
To: LKML <linux-kernel@vger.kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>,
x86@kernel.org, Lu Baolu <baolu.lu@linux.intel.com>,
iommu@lists.linux.dev,
Michael Grzeschik <m.grzeschik@pengutronix.de>,
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"David S. Miller" <davem@davemloft.net>,
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Subject: [patch 08/38] x86/tsc: Use rdtsc() instead of get_cycles()
Date: Fri, 10 Apr 2026 14:19:08 +0200 [thread overview]
Message-ID: <20260410120318.121043259@kernel.org> (raw)
In-Reply-To: <20260410120044.031381086@kernel.org>
This code knows that TSC is available so there is no point to use the TSC
feature guarded get_cycles().
No functional change.
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
---
arch/x86/kernel/tsc.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -371,12 +371,12 @@ static u64 tsc_read_refs(u64 *p, int hpe
int i;
for (i = 0; i < MAX_RETRIES; i++) {
- t1 = get_cycles();
+ t1 = rdtsc();
if (hpet)
*p = hpet_readl(HPET_COUNTER) & 0xFFFFFFFF;
else
*p = acpi_pm_read_early();
- t2 = get_cycles();
+ t2 = rdtsc();
if ((t2 - t1) < thresh)
return t2;
}
@@ -468,13 +468,13 @@ static unsigned long pit_calibrate_tsc(u
outb(latch & 0xff, 0x42);
outb(latch >> 8, 0x42);
- tsc = t1 = t2 = get_cycles();
+ tsc = t1 = t2 = rdtsc();
pitcnt = 0;
tscmax = 0;
tscmin = ULONG_MAX;
while ((inb(0x61) & 0x20) == 0) {
- t2 = get_cycles();
+ t2 = rdtsc();
delta = t2 - tsc;
tsc = t2;
if ((unsigned long) delta < tscmin)
@@ -553,9 +553,9 @@ static inline int pit_expect_msb(unsigne
if (!pit_verify_msb(val))
break;
prev_tsc = tsc;
- tsc = get_cycles();
+ tsc = rdtsc();
}
- *deltap = get_cycles() - prev_tsc;
+ *deltap = rdtsc() - prev_tsc;
*tscp = tsc;
/*
next prev parent reply other threads:[~2026-04-10 12:19 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-04-10 12:18 [patch 00/38] treewide: Cleanup LATCH, CLOCK_TICK_RATE and get_cycles() [ab]use Thomas Gleixner
2026-04-10 12:18 ` [patch 01/38] percpu: Sanitize __percpu_qual include hell Thomas Gleixner
2026-04-10 12:18 ` [patch 02/38] x86: Cleanup include recursion hell Thomas Gleixner
2026-04-10 12:18 ` [patch 03/38] x86/apm: Remove last LATCH usage Thomas Gleixner
2026-04-10 12:18 ` [patch 04/38] x86: Use PIT_TICK_RATE instead of CLOCK_TICK_RATE Thomas Gleixner
2026-04-10 12:18 ` [patch 05/38] treewide: Remove CLOCK_TICK_RATE Thomas Gleixner
2026-04-10 12:18 ` [patch 06/38] calibrate: Rework delay timer calibration Thomas Gleixner
2026-04-10 12:19 ` [patch 07/38] treewide: Consolidate cycles_t Thomas Gleixner
2026-04-10 12:19 ` Thomas Gleixner [this message]
2026-04-10 12:19 ` [patch 09/38] iommu/vt-d: Use sched_clock() instead of get_cycles() Thomas Gleixner
2026-04-10 13:45 ` Baolu Lu
2026-04-10 15:14 ` Thomas Gleixner
2026-04-10 12:19 ` [patch 10/38] arcnet: Remove function timing code Thomas Gleixner
2026-04-10 12:19 ` [patch 11/38] misc: sgi-gru: Remove get_cycles() [ab]use Thomas Gleixner
2026-04-10 12:19 ` [patch 12/38] wifi: wil6210: Replace get_cyles() usage Thomas Gleixner
2026-04-10 12:19 ` [patch 13/38] crypto: tcrypt: Replace get_cycles() with ktime_get() Thomas Gleixner
2026-04-10 12:19 ` [patch 14/38] slub: Use prandom instead of get_cycles() Thomas Gleixner
2026-04-10 12:19 ` [patch 15/38] ptp: ptp_vmclock: Replace get_cycles() usage Thomas Gleixner
2026-04-10 12:19 ` [patch 16/38] fbdev: udlfb: Replace get_cycles() with ktime_get() Thomas Gleixner
2026-04-10 12:19 ` [patch 17/38] ext4: Replace get_cycles() usage " Thomas Gleixner
2026-04-10 12:19 ` [patch 18/38] lib/tests: Replace get_cycles() " Thomas Gleixner
2026-04-10 12:20 ` [patch 19/38] kcsan: Replace get_cycles() usage Thomas Gleixner
2026-04-10 13:39 ` Marco Elver
2026-04-10 12:20 ` [patch 20/38] kasan: sw_tags: Replace get_cycles() by random_get_entropy() Thomas Gleixner
2026-04-10 12:20 ` [patch 21/38] hamradio: baycom_epp: Remove BAYCOM_DEBUG Thomas Gleixner
2026-04-10 12:20 ` [patch 22/38] random: Provide CONFIG_ARCH_HAS_RANDOM_ENTROPY Thomas Gleixner
2026-04-10 12:20 ` [patch 23/38] alpha: Select ARCH_HAS_RANDOM_ENTROPY Thomas Gleixner
2026-04-10 12:20 ` [patch 24/38] ARM: " Thomas Gleixner
2026-04-10 12:20 ` [patch 25/38] arm64: " Thomas Gleixner
2026-04-10 12:20 ` [patch 26/38] loongarch: " Thomas Gleixner
2026-04-10 12:20 ` [patch 27/38] m68k: " Thomas Gleixner
2026-04-10 15:31 ` Daniel Palmer
2026-04-10 12:20 ` [patch 28/38] mips: " Thomas Gleixner
2026-04-10 12:20 ` [patch 29/38] nios2: " Thomas Gleixner
2026-04-10 12:20 ` [patch 30/38] openrisc: " Thomas Gleixner
2026-04-10 12:21 ` [patch 31/38] parisc: " Thomas Gleixner
2026-04-10 12:21 ` [patch 32/38] powerpc/spufs: Use mftb() directly Thomas Gleixner
2026-04-10 12:21 ` [patch 33/38] powerpc: Select ARCH_HAS_RANDOM_ENTROPY Thomas Gleixner
2026-04-10 12:21 ` [patch 34/38] riscv: " Thomas Gleixner
2026-04-10 12:21 ` [patch 35/38] s390: " Thomas Gleixner
2026-04-10 12:21 ` [patch 36/38] sparc: Select ARCH_HAS_RANDOM_ENTROPY for SPARC64 Thomas Gleixner
2026-04-10 12:21 ` [patch 37/38] x86: Select ARCH_HAS_RANDOM_ENTROPY Thomas Gleixner
2026-04-10 12:21 ` [patch 38/38] treewide: Remove asm/timex.h includes from generic code Thomas Gleixner
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