Messages in this thread Patch in this message | | | Date | Tue, 23 Sep 2008 11:15:47 +0200 | From | Ingo Molnar <> | Subject | Re: [PATCH] raid: make RAID autodetect default a KConfig option |
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* Arjan van de Ven <arjan@infradead.org> wrote:
> On Tue, 23 Sep 2008 13:45:19 +1000 > Neil Brown <neilb@suse.de> wrote: > > > On Monday September 22, mingo@elte.hu wrote: > > > > > > * Arjan van de Ven <arjan@infradead.org> wrote: > > > > > > > From 812bf9a448d96375a3aec5c51764d74cace85abb Mon Sep 17 00:00:00 > > > > 2001 From: Arjan van de Ven <arjan@linux.intel.com> > > > > Date: Sun, 21 Sep 2008 15:44:32 -0700 > > > > Subject: [PATCH] raid: make RAID autodetect default a KConfig > > > > option > > > > > > > > RAID autodetect has the side effect of requiring synchronisation > > > > of all device drivers, which can make the boot several seconds > > > > longer (I've measured 7 on one of my laptops).... even for > > > > systems that don't have RAID setup for the root filesystem (the > > > > only FS where this matters). > > > > > > > > This patch makes the default for autodetect a config option; > > > > either way the user can always override via the kernel command > > > > line. > > > > > > Neil, if you agree with this patch, could you please send your > > > Acked-by line? This patch depends on a clean-up in > > > init/do_mounts_md.c that is in the fastboot tree so it would be > > > logistically easier/better if we could queue this up towards > > > upstream via tip/fastboot. > > > > Yes, > > Acked-by: NeilBrown <neilb@suse.de> > > > > I'm not a big fan of autodetect in any case, and this patch seems to > > cover all the bases I can think of. > > > > thanks > pushed to > git://git.kernel.org/pub/scm/linux/kernel/git/arjan/linux-2.6-fastboot.git > master > > Ingo, please pull
pulled the commit below into tip/fastboot, thanks Arjan and Neil!
Ingo
----------------> From da827bea62d62cabfe913e05fc05879faa614af8 Mon Sep 17 00:00:00 2001 From: Arjan van de Ven <arjan@linux.intel.com> Date: Sun, 21 Sep 2008 15:44:32 -0700 Subject: [PATCH] raid: make RAID autodetect default a KConfig option
RAID autodetect has the side effect of requiring synchronisation of all device drivers, which can make the boot several seconds longer (I've measured 7 on one of my laptops).... even for systems that don't have RAID setup for the root filesystem (the only FS where this matters).
This patch makes the default for autodetect a config option; either way the user can always override via the kernel command line.
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com> Acked-by: NeilBrown <neilb@suse.de> --- drivers/md/Kconfig | 14 ++++++++++++++ init/do_mounts_md.c | 11 +++++++++-- 2 files changed, 23 insertions(+), 2 deletions(-)
diff --git a/drivers/md/Kconfig b/drivers/md/Kconfig index 07d92c1..8e72c91 100644 --- a/drivers/md/Kconfig +++ b/drivers/md/Kconfig @@ -30,6 +30,20 @@ config BLK_DEV_MD If unsure, say N. +config MD_AUTODETECT + bool "Autodetect RAID arrays during kernel boot" + depends on BLK_DEV_MD + default y + ---help--- + If you say Y here, then the kernel will try to autodetect raid + arrays as part of its boot process. + + If you don't use raid and say Y, this autodetection can cause + a several-second delay in the boot time due to various + synchronisation steps that are part of this step. + + If unsure, say Y. + config MD_LINEAR tristate "Linear (append) mode" depends on BLK_DEV_MD diff --git a/init/do_mounts_md.c b/init/do_mounts_md.c index c0dfd3c..48b3fad 100644 --- a/init/do_mounts_md.c +++ b/init/do_mounts_md.c @@ -12,7 +12,12 @@ * The code for that is here. */ -static int __initdata raid_noautodetect, raid_autopart; +#ifdef CONFIG_MD_AUTODETECT +static int __initdata raid_noautodetect; +#else +static int __initdata raid_noautodetect=1; +#endif +static int __initdata raid_autopart; static struct { int minor; @@ -252,6 +257,8 @@ static int __init raid_setup(char *str) if (!strncmp(str, "noautodetect", wlen)) raid_noautodetect = 1; + if (!strncmp(str, "autodetect", wlen)) + raid_noautodetect = 0; if (strncmp(str, "partitionable", wlen)==0) raid_autopart = 1; if (strncmp(str, "part", wlen)==0) @@ -288,7 +295,7 @@ void __init md_run_setup(void) create_dev("/dev/md0", MKDEV(MD_MAJOR, 0)); if (raid_noautodetect) - printk(KERN_INFO "md: Skipping autodetection of RAID arrays. (raid=noautodetect)\n"); + printk(KERN_INFO "md: Skipping autodetection of RAID arrays. (raid=autodetect will force)\n"); else autodetect_raid(); md_setup_drive();
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