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Commit be85f93a authored by Daniel Verkamp's avatar Daniel Verkamp Committed by Shaohua Li
Browse files

lib/raid6: add option to skip algo benchmarking 



This is helpful for systems where fast startup time is important.
It is especially nice to avoid benchmarking RAID functions that are
never used (for example, BTRFS selects RAID6_PQ even if the parity RAID
mode is not in use).

This saves 250+ milliseconds of boot time on modern x86 and ARM systems
with a dozen or more available implementations.

The new option is defaulted to 'y' to match the previous behavior of
always benchmarking on init.

Signed-off-by: default avatarDaniel Verkamp <dverkamp@chromium.org>
Signed-off-by: default avatarShaohua Li <shli@fb.com>
parent 0437de4f

include/linux/raid/pq.h

+3 −0
Original line number Diff line number Diff line
@@ -70,6 +70,9 @@ extern const char raid6_empty_zero_page[PAGE_SIZE]; 
#define MODULE_DESCRIPTION(desc)

#define subsys_initcall(x)

#define module_exit(x)



#define IS_ENABLED(x) (x)

#define CONFIG_RAID6_PQ_BENCHMARK 1

#endif /* __KERNEL__ */



/* Routine choices */

lib/Kconfig

+8 −0
Original line number Diff line number Diff line
@@ -10,6 +10,14 @@ menu "Library routines" 
config RAID6_PQ

	tristate



config RAID6_PQ_BENCHMARK

	bool "Automatically choose fastest RAID6 PQ functions"

	depends on RAID6_PQ

	default y

	help

	  Benchmark all available RAID6 PQ functions on init and choose the

	  fastest one.



config BITREVERSE

	tristate

lib/raid6/algos.c

+5 −0
Original line number Diff line number Diff line
@@ -163,6 +163,11 @@ static inline const struct raid6_calls *raid6_choose_gen( 
			if ((*algo)->valid && !(*algo)->valid())

				continue;



			if (!IS_ENABLED(CONFIG_RAID6_PQ_BENCHMARK)) {

				best = *algo;

				break;

			}



			perf = 0;



			preempt_disable();