From: Hayato Ohhashi <o8@vmm.dev>
To: tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, x86@kernel.org
Cc: xen-devel@lists.xenproject.org, linux-kernel@vger.kernel.org,
boris.ostrovsky@oracle.com, jgross@suse.com,
sstabellini@kernel.org, Hayato Ohhashi <o8@vmm.dev>
Subject: [PATCH] x86/xen/time: set the X86_FEATURE_TSC_KNOWN_FREQ flag in xen_tsc_khz()
Date: Tue, 21 Jul 2020 16:12:31 +0000 [thread overview]
Message-ID: <20200721161231.6019-1-o8@vmm.dev> (raw)
If the TSC frequency is known from the pvclock page,
the TSC frequency does not need to be recalibrated.
We can avoid recalibration by setting X86_FEATURE_TSC_KNOWN_FREQ.
Signed-off-by: Hayato Ohhashi <o8@vmm.dev>
---
arch/x86/xen/time.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/arch/x86/xen/time.c b/arch/x86/xen/time.c
index c8897aad13cd..91f5b330dcc6 100644
--- a/arch/x86/xen/time.c
+++ b/arch/x86/xen/time.c
@@ -39,6 +39,7 @@ static unsigned long xen_tsc_khz(void)
struct pvclock_vcpu_time_info *info =
&HYPERVISOR_shared_info->vcpu_info[0].time;
+ setup_force_cpu_cap(X86_FEATURE_TSC_KNOWN_FREQ);
return pvclock_tsc_khz(info);
}
--
2.23.3
WARNING: multiple messages have this Message-ID (diff)
From: Hayato Ohhashi <o8@vmm.dev>
To: tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, x86@kernel.org
Cc: jgross@suse.com, Hayato Ohhashi <o8@vmm.dev>,
sstabellini@kernel.org, linux-kernel@vger.kernel.org,
xen-devel@lists.xenproject.org, boris.ostrovsky@oracle.com
Subject: [PATCH] x86/xen/time: set the X86_FEATURE_TSC_KNOWN_FREQ flag in xen_tsc_khz()
Date: Tue, 21 Jul 2020 16:12:31 +0000 [thread overview]
Message-ID: <20200721161231.6019-1-o8@vmm.dev> (raw)
If the TSC frequency is known from the pvclock page,
the TSC frequency does not need to be recalibrated.
We can avoid recalibration by setting X86_FEATURE_TSC_KNOWN_FREQ.
Signed-off-by: Hayato Ohhashi <o8@vmm.dev>
---
arch/x86/xen/time.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/arch/x86/xen/time.c b/arch/x86/xen/time.c
index c8897aad13cd..91f5b330dcc6 100644
--- a/arch/x86/xen/time.c
+++ b/arch/x86/xen/time.c
@@ -39,6 +39,7 @@ static unsigned long xen_tsc_khz(void)
struct pvclock_vcpu_time_info *info =
&HYPERVISOR_shared_info->vcpu_info[0].time;
+ setup_force_cpu_cap(X86_FEATURE_TSC_KNOWN_FREQ);
return pvclock_tsc_khz(info);
}
--
2.23.3
next reply other threads:[~2020-07-21 16:13 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-21 16:12 Hayato Ohhashi [this message]
2020-07-21 16:12 ` [PATCH] x86/xen/time: set the X86_FEATURE_TSC_KNOWN_FREQ flag in xen_tsc_khz() Hayato Ohhashi
2020-07-21 23:33 ` Boris Ostrovsky
2020-07-21 23:33 ` Boris Ostrovsky
2020-07-25 13:53 ` [tip: x86/timers] x86/xen/time: Set " tip-bot2 for Hayato Ohhashi
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