> -----Original Message----- > From: linux-omap-owner@xxxxxxxxxxxxxxx [mailto:linux-omap- > owner@xxxxxxxxxxxxxxx] On Behalf Of Tony Lindgren > Sent: Wednesday, September 08, 2010 8:44 AM > To: Russell King - ARM Linux > Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; linux-omap@xxxxxxxxxxxxxxx; > bryan.wu@xxxxxxxxxxxxx > Subject: [PATCH] ARM: Don't try to send IPI on UP systems with CONFIG_SMP > > This is not needed on UP. Additionally with will cause issues when > booting CONFIG_SMP_ON_UP kernel on earlier ARM cores. > > Signed-off-by: Tony Lindgren <tony@xxxxxxxxxxx> > > diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c > index 401e38b..5facdbe 100644 > --- a/arch/arm/kernel/process.c > +++ b/arch/arm/kernel/process.c > @@ -207,9 +207,7 @@ __setup("reboot=", reboot_setup); > > void machine_shutdown(void) > { > -#ifdef CONFIG_SMP > smp_send_stop(); > -#endif > } > > void machine_halt(void) > diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c > index 40dc74f..16ca27b 100644 > --- a/arch/arm/kernel/smp.c > +++ b/arch/arm/kernel/smp.c > @@ -560,12 +560,17 @@ asmlinkage void __exception do_IPI(struct pt_regs > *regs) > > void smp_send_reschedule(int cpu) > { > - send_ipi_message(cpumask_of(cpu), IPI_RESCHEDULE); > + if (is_smp()) > + send_ipi_message(cpumask_of(cpu), IPI_RESCHEDULE); > } > > void smp_send_stop(void) > { > cpumask_t mask = cpu_online_map; > + > + if (!is_smp()) > + return; > + > cpu_clear(smp_processor_id(), mask); > send_ipi_message(&mask, IPI_CPU_STOP); > } The IPI is called too many times, and a check in this path might be an overhead. Can we runtime make " smp_send_reschedule" etc NULL based on it's UP or SMP boot ? Regards Santosh -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
