smp: Micro-optimize smp_call_function_many_cond()

Peter Zijlstra · Ingo Molnar · commit d43f17a1da25 · 2021-03-06T13:00:22.000+01:00
Call the generic send_call_function_single_ipi() function, which
will avoid the IPI when @last_cpu is idle.

Signed-off-by: Peter Zijlstra &lt;peterz@infradead.org&gt;
Signed-off-by: Ingo Molnar &lt;mingo@kernel.org&gt;
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar &lt;mingo@kernel.org&gt;
diff --git a/kernel/smp.c b/kernel/smp.c
@@ -694,7 +694,7 @@ static void smp_call_function_many_cond(const struct cpumask *mask,
 		 * provided mask.
 		 */
 		if (nr_cpus == 1)
-			arch_send_call_function_single_ipi(last_cpu);
+			send_call_function_single_ipi(last_cpu);
 		else if (likely(nr_cpus > 1))
 			arch_send_call_function_ipi_mask(cfd->cpumask_ipi);
 	}

Original file line number	Diff line number	Diff line change
`@@ -694,7 +694,7 @@ static void smp_call_function_many_cond(const struct cpumask *mask,`
`694`	`694`	`* provided mask.`
`695`	`695`	`*/`
`696`	`696`	`if (nr_cpus == 1)`
`697`		`- arch_send_call_function_single_ipi(last_cpu);`
	`697`	`+ send_call_function_single_ipi(last_cpu);`
`698`	`698`	`else if (likely(nr_cpus > 1))`
`699`	`699`	`arch_send_call_function_ipi_mask(cfd->cpumask_ipi);`
`700`	`700`	`}`