From be85f93ae2df32dea0b20908316f1d894c3e0f64 Mon Sep 17 00:00:00 2001 From: Daniel Verkamp Date: Mon, 12 Nov 2018 15:26:52 -0800 Subject: 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: Daniel Verkamp Signed-off-by: Shaohua Li --- include/linux/raid/pq.h | 3 +++ lib/Kconfig | 8 ++++++++ lib/raid6/algos.c | 5 +++++ 3 files changed, 16 insertions(+) diff --git a/include/linux/raid/pq.h b/include/linux/raid/pq.h index d7c99161bba2..605cf46c17bd 100644 --- a/include/linux/raid/pq.h +++ b/include/linux/raid/pq.h @@ -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 */ diff --git a/lib/Kconfig b/lib/Kconfig index a9965f4af4dd..fcb05305a5a2 100644 --- a/lib/Kconfig +++ b/lib/Kconfig @@ -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 diff --git a/lib/raid6/algos.c b/lib/raid6/algos.c index a753ff56670f..7e4f7a8ffa8e 100644 --- a/lib/raid6/algos.c +++ b/lib/raid6/algos.c @@ -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(); -- cgit v1.2.3-70-g09d2