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From: Yu Zhe <yuzhe@nfschina.com>
To: tglx@linutronix.de, mingo@redhat.com, bp@alien8.de,
	dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com
Cc: linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org,
	liqiong@nfschina.com, Yu Zhe <yuzhe@nfschina.com>
Subject: [PATCH] x86/aperfmperf: use time_is_before_jiffies(a + b) to replace "jiffies - a > b"
Date: Wed, 27 Jul 2022 11:14:05 +0800	[thread overview]
Message-ID: <20220727031405.26892-1-yuzhe@nfschina.com> (raw)

time_is_before_jiffies deals with timer wrapping correctly.

Signed-off-by: Yu Zhe <yuzhe@nfschina.com>
---
 arch/x86/kernel/cpu/aperfmperf.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/aperfmperf.c b/arch/x86/kernel/cpu/aperfmperf.c
index 1f60a2b27936..22e0bac3fffe 100644
--- a/arch/x86/kernel/cpu/aperfmperf.c
+++ b/arch/x86/kernel/cpu/aperfmperf.c
@@ -423,7 +423,7 @@ unsigned int arch_freq_get_on_cpu(int cpu)
 	 * Bail on invalid count and when the last update was too long ago,
 	 * which covers idle and NOHZ full CPUs.
 	 */
-	if (!mcnt || (jiffies - last) > MAX_SAMPLE_AGE)
+	if (!mcnt || time_is_before_jiffies(last + MAX_SAMPLE_AGE))
 		goto fallback;
 
 	return div64_u64((cpu_khz * acnt), mcnt);
-- 
2.11.0


             reply	other threads:[~2022-07-27  3:15 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-07-27  3:14 Yu Zhe [this message]
2022-07-27 16:00 ` [PATCH] x86/aperfmperf: use time_is_before_jiffies(a + b) to replace "jiffies - a > b" Peter Zijlstra
2022-07-28  2:55   ` Yu Zhe
2022-07-28 10:30     ` Peter Zijlstra

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