Re: USB storage no-boot regression (bisected)
[Posted April 15, 2009 by corbet]
| From: |
| Alan Cox <alan-qBU/x9rampVanCEyBjwyrvXRex20P6io-AT-public.gmane.org> |
| To: |
| Mark Lord <lkml-gsilrlXbHYg-AT-public.gmane.org> |
| Subject: |
| Re: USB storage no-boot regression (bisected) |
| Date: |
| Wed, 15 Apr 2009 16:01:53 +0100 |
| Message-ID: |
| <20090415160153.485c2095@lxorguk.ukuu.org.uk> |
| Cc: |
| Greg KH <greg-U8xfFu+wG4EAvxtiuMwx3w-AT-public.gmane.org>, Jeff Garzik <jeff-o2qLIJkoznsdnm+yROfE0A-AT-public.gmane.org>,
Linux USB kernel mailing list <linux-usb-u79uwXL29TY76Z2rM5mHXA-AT-public.gmane.org>,
Alan Stern <stern-nwvwT67g6+6dFdvTe/nMLpVzexx5G7lz-AT-public.gmane.org>,
LKML <linux-kernel-u79uwXL29TY76Z2rM5mHXA-AT-public.gmane.org>,
"Rafael J. Wysocki" <rjw-KKrjLPT3xs0-AT-public.gmane.org>,
Arjan van de Ven <arjan-wEGCiKHe2LqWVfeAwA7xHQ-AT-public.gmane.org> |
| Archive-link: |
| Article, Thread
|
> SATA drives also take variable amounts of time to "show up" at boot.
> Perhaps Jeff should customize libata for your and Arjan's exact setups,
> just to help with understanding the point here. :)
Actually I would argue the reverse. The sooner we can push this so that
libata isn't blocking mounting the rootfs the better.
> The speed ups are fine (and welcome), but we really now need
> Arjan to follow-up with a patch to have the kernel *by default*
> wait a little longer for the rootfs to show up.
>
> Not forever, just a few seconds to compensate for the regression.
Why should every user suffer a slower boot and a poorer resume time ?
Instead make the root fs mounting look like this
while(my_rootfs_hasnt_appeared_and_i_am_sad()) {
wait_on(&new_disk_discovery);
}
and poke the queue whenever we add a relevant device.
That way if you are booting off an initrd you can finish the SATA probe
in parallel to getting userspace ticking over.
On what is nowdays essentially a hot plug system it all needs turning
this way up - eg RAID volumes should assemble and come online as the
drives are discovered not at some fixed point later in userspace.
Alan
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