From 1307ca29e127fffb24984456bc1e407888fc3d66 Mon Sep 17 00:00:00 2001 From: Daniel Verkamp Date: Mon, 12 Nov 2018 15:26:52 -0800 Subject: [PATCH] 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 [jhoon20.kim: backport from mainline for the fast kernel startup] Change-Id: I38c270c413d60de65f27cf9c95d44bb2e2d07ac2 Signed-off-by: Junghoon Kim --- 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 ea8505204fdf..faf7a4529a5a 100644 --- a/include/linux/raid/pq.h +++ b/include/linux/raid/pq.h @@ -67,6 +67,9 @@ 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 a3928d4438b5..fcb00bc06f1a 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 5065b1e7e327..c34344902fd2 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(); -- 2.34.1