linux-kernel - [PATCH v2] x86/xen/time: Reduce Xen timer tick

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Message-ID: <20240619104015.30477-1-frediano.ziglio@cloud.com>
Date: Wed, 19 Jun 2024 11:40:15 +0100
From: Frediano Ziglio <frediano.ziglio@...ud.com>
To: xen-devel@...ts.xenproject.org,
	linux-kernel@...r.kernel.org
Cc: "H. Peter Anvin" <hpa@...or.com>,
	x86@...nel.org,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	Borislav Petkov <bp@...en8.de>,
	Ingo Molnar <mingo@...hat.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Boris Ostrovsky <boris.ostrovsky@...cle.com>,
	Juergen Gross <jgross@...e.com>,
	Frediano Ziglio <frediano.ziglio@...ud.com>
Subject: [PATCH v2] x86/xen/time: Reduce Xen timer tick

Current timer tick is causing some deadline to fail.
The current high value constant was probably due to an old
bug in the Xen timer implementation causing errors if the
deadline was in the future.

This was fixed in Xen commit:
19c6cbd90965 xen/vcpu: ignore VCPU_SSHOTTMR_future

Usage of VCPU_SSHOTTMR_future in Linux kernel was removed by:
c06b6d70feb3 xen/x86: don't lose event interrupts

Signed-off-by: Frediano Ziglio <frediano.ziglio@...ud.com>
---
 arch/x86/xen/time.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Changes since v1:
- Update commit message;
- reduce delay.

diff --git a/arch/x86/xen/time.c b/arch/x86/xen/time.c
index 52fa5609b7f6..96521b1874ac 100644
--- a/arch/x86/xen/time.c
+++ b/arch/x86/xen/time.c
@@ -30,7 +30,7 @@
 #include "xen-ops.h"
 
 /* Minimum amount of time until next clock event fires */
-#define TIMER_SLOP	100000
+#define TIMER_SLOP	1
 
 static u64 xen_sched_clock_offset __read_mostly;
 
-- 
2.45.1