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Commit f70ddc07 authored by James Hogan's avatar James Hogan Committed by Ralf Baechle
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MIPS: c-r4k: Avoid small flush_icache_range SMP calls 



Avoid SMP calls for flushing small icache ranges. On non-CM platforms,
and CM platforms too after we make r4k_on_each_cpu() take the cache op
type into account, it will be called on multiple CPUs due to the
possibility that local_r4k_flush_icache_range_ipi() could do
non-globalized indexed cache ops. This rougly copies the range size
check out into r4k_flush_icache_range(), which can disallow indexed
cache ops and allow r4k_on_each_cpu() to skip the SMP call.

Signed-off-by: default avatarJames Hogan <james.hogan@imgtec.com>
Cc: Paul Burton <paul.burton@imgtec.com>
Cc: Leonid Yegoshin <leonid.yegoshin@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/13805/


Signed-off-by: default avatarRalf Baechle <ralf@linux-mips.org>
parent 27b93d9c

arch/mips/mm/c-r4k.c

+21 −0
Original line number Diff line number Diff line
@@ -784,12 +784,33 @@ static inline void local_r4k_flush_icache_range_ipi(void *args) 
static void r4k_flush_icache_range(unsigned long start, unsigned long end)

{

	struct flush_icache_range_args args;

	unsigned long size, cache_size;



	args.start = start;

	args.end = end;

	args.type = R4K_HIT | R4K_INDEX;



	/*

	 * Indexed cache ops require an SMP call.

	 * Consider if that can or should be avoided.

	 */

	preempt_disable();

	if (r4k_op_needs_ipi(R4K_INDEX) && !r4k_op_needs_ipi(R4K_HIT)) {

		/*

		 * If address-based cache ops don't require an SMP call, then

		 * use them exclusively for small flushes.

		 */

		size = start - end;

		cache_size = icache_size;

		if (!cpu_has_ic_fills_f_dc) {

			size *= 2;

			cache_size += dcache_size;

		}

		if (size <= cache_size)

			args.type &= ~R4K_INDEX;

	}

	r4k_on_each_cpu(args.type, local_r4k_flush_icache_range_ipi, &args);

	preempt_enable();

	instruction_hazard();

}