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([2603:8080:7400:36da:dff5:4180:2562:4c1e]) by smtp.gmail.com with ESMTPSA id 46e09a7af769-72bb269dfbesm1765657a34.22.2025.03.17.15.01.23 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 17 Mar 2025 15:01:23 -0700 (PDT) Message-ID: Date: Mon, 17 Mar 2025 17:01:22 -0500 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Content-Language: en-US To: pmladek@suse.com, Andrew Morton , jani.nikula@intel.com, open list , Greg Kroah-Hartman , Thomas Gleixner , takakura@valinux.co.jp, john.ogness@linutronix.de From: Carlos Bilbao Subject: [RFC] panic: reduce CPU consumption when finished handling panic Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable After the kernel has finished handling a panic, it enters a busy-wait loop. But, this unnecessarily consumes CPU power and electricity. Plus, in VMs, this negatively impacts the throughput of other VM guests running on the same hypervisor. I propose introducing a function cpu_halt_end_panic() to halt the CPU during this state while still allowing interrupts to be processed. See my commit below. Thanks in advance! Signed-off-by: Carlos Bilbao --- =C2=A0kernel/panic.c | 17 ++++++++++++++++- =C2=A01 file changed, 16 insertions(+), 1 deletion(-) diff --git a/kernel/panic.c b/kernel/panic.c index fbc59b3b64d0..c00ccaa698d5 100644 --- a/kernel/panic.c +++ b/kernel/panic.c @@ -276,6 +276,21 @@ static void panic_other_cpus_shutdown(bool crash_kexec) =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 crash_smp_send_stop(); =C2=A0} =C2=A0 +static void cpu_halt_end_panic(void) +{ +#ifdef CONFIG_X86 +=C2=A0=C2=A0=C2=A0 native_safe_halt(); +#elif defined(CONFIG_ARM) +=C2=A0=C2=A0=C2=A0 cpu_do_idle(); +#else +=C2=A0=C2=A0=C2=A0 /* +=C2=A0=C2=A0=C2=A0=C2=A0 * Default to a simple busy-wait if no architectur= e-specific halt is +=C2=A0=C2=A0=C2=A0=C2=A0 * defined above +=C2=A0=C2=A0=C2=A0=C2=A0 */ +=C2=A0=C2=A0=C2=A0 mdelay(PANIC_TIMER_STEP); +#endif +} + =C2=A0/** =C2=A0 *=C2=A0=C2=A0=C2=A0 panic - halt the system =C2=A0 *=C2=A0=C2=A0=C2=A0 @fmt: The text string to print @@ -474,7 +489,7 @@ void panic(const char *fmt, ...) =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 i = +=3D panic_blink(state ^=3D 1); =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 i_= next =3D i + 3600 / PANIC_BLINK_SPD; =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 } -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 mdelay(PANIC_TIMER_STEP); +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 cpu_halt_end_panic(); =C2=A0=C2=A0=C2=A0=C2=A0 } =C2=A0} =C2=A0 --=20 2.47.1