[<prev] [next>] [<thread-prev] [day] [month] [year] [list]
Message-ID: <20250326151204.67898-2-carlos.bilbao@kernel.org>
Date: Wed, 26 Mar 2025 10:12:03 -0500
From: carlos.bilbao@...nel.org
To: tglx@...utronix.de
Cc: bilbao@...edu,
pmladek@...e.com,
akpm@...ux-foundation.org,
jan.glauber@...il.com,
jani.nikula@...el.com,
linux-kernel@...r.kernel.org,
gregkh@...uxfoundation.org,
takakura@...inux.co.jp,
john.ogness@...utronix.de,
Carlos Bilbao <carlos.bilbao@...nel.org>
Subject: [PATCH 1/2] panic: Allow archs to reduce CPU consumption after panic
From: Carlos Bilbao <carlos.bilbao@...nel.org>
After handling a panic, the kernel enters a busy-wait loop, unnecessarily
consuming CPU and potentially impacting other workloads including other
guest VMs in the case of virtualized setups.
Introduce cpu_halt_after_panic(), a weak function that archs can override
for a more efficient halt of CPU work. By default, it preserves the
pre-existing behavior of delay.
Signed-off-by: Carlos Bilbao (DigitalOcean) <carlos.bilbao@...nel.org>
Reviewed-by: Jan Glauber (DigitalOcean) <jan.glauber@...il.com>
---
kernel/panic.c | 12 +++++++++++-
1 file changed, 11 insertions(+), 1 deletion(-)
diff --git a/kernel/panic.c b/kernel/panic.c
index fbc59b3b64d0..fafe3fa22533 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -276,6 +276,16 @@ static void panic_other_cpus_shutdown(bool crash_kexec)
crash_smp_send_stop();
}
+/*
+ * Called after a kernel panic has been handled, at which stage halting
+ * the CPU can help reduce unnecessary CPU consumption. In the absence of
+ * arch-specific implementations, just delay
+ */
+static void __weak cpu_halt_after_panic(void)
+{
+ mdelay(PANIC_TIMER_STEP);
+}
+
/**
* panic - halt the system
* @fmt: The text string to print
@@ -474,7 +484,7 @@ void panic(const char *fmt, ...)
i += panic_blink(state ^= 1);
i_next = i + 3600 / PANIC_BLINK_SPD;
}
- mdelay(PANIC_TIMER_STEP);
+ cpu_halt_after_panic();
}
}
--
2.47.1
Powered by blists - more mailing lists