From: Greg KH <greg@kroah.com>
To: Tim Bird <tim.bird@am.sony.com>, Jeff Mahoney <jeffm@suse.de>
Cc: Christoph Hellwig <hch@infradead.org>,
Alessio Igor Bogani <abogani@kernel.org>,
Rusty Russell <rusty@rustcorp.com.au>,
Anders Kaseorg <andersk@ksplice.com>,
Tim Abbott <tabbott@ksplice.com>,
LKML <linux-kernel@vger.kernel.org>,
Linux Embedded <linux-embedded@vger.kernel.org>,
Jason Wessel <jason.wessel@windriver.com>,
Dirk Behme <dirk.behme@googlemail.com>
Subject: Re: module boot time (was Re: [PATCH] module: Use binary search in lookup_symbol())
Date: Wed, 18 May 2011 14:34:51 -0700 [thread overview]
Message-ID: <20110518213451.GA23702@kroah.com> (raw)
In-Reply-To: <4DD435B7.9090702@am.sony.com>
On Wed, May 18, 2011 at 02:10:15PM -0700, Tim Bird wrote:
> >>> And why do people overly care for the load time?
> >>
> >> To reduce overall boot time.
> >
> > To reduce it even more, build the modules into the kernel :)
>
> That's what I do most of the time. For some projects,
> it is useful to build certain things as modules so you can
> defer initializing them until later in the boot sequence.
> You can get some critical user-space tasks running, then
> come back later to initialize USB and other drivers.
> On cameras, it's not uncommon to want to get to user
> space in the first 500 milliseconds.
That's common even on desktops and servers, and using the bootchart code
in the kernel helps find those bottlenecks.
> Sony has some code which allows us to both statically link
> drivers and defer their initialization, but it's kind of
> kludgy and requires modifying the module declarations
> for the code you want to defer. Let me know if you think
> this is worth doing an RFC about.
I don't think that's worth it, there has been talk, and some initial
code, about adding kernel modules to the kernel image itself, which
would solve a lot of the i/o time of loading modules, and solves some
other boot speed problems. That work was done by Jeff Mahoney, but I
think he ran into some "interesting" linker issues and had to shelve it
due to a lack of time :(
thanks,
greg k-h
next prev parent reply other threads:[~2011-05-18 21:35 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-05-03 20:42 [PATCH] module: Use binary search in lookup_symbol() Alessio Igor Bogani
2011-05-04 15:34 ` Dirk Behme
2011-05-04 17:30 ` Alessio Igor Bogani
2011-05-16 15:36 ` Dirk Behme
2011-05-16 18:02 ` Anders Kaseorg
2011-05-16 20:23 ` Alessio Igor Bogani
2011-05-16 21:01 ` Joe Perches
2011-05-16 21:08 ` Joe Perches
2011-05-17 3:52 ` Rusty Russell
2011-05-17 19:18 ` Dirk Behme
2011-05-17 19:41 ` Alessio Igor Bogani
2011-05-17 20:56 ` Alessio Igor Bogani
2011-05-17 23:22 ` Greg KH
2011-05-17 23:33 ` Tim Bird
2011-05-18 7:54 ` Christoph Hellwig
2011-05-18 17:00 ` Tim Bird
2011-05-18 19:21 ` Greg KH
2011-05-18 21:10 ` module boot time (was Re: [PATCH] module: Use binary search in lookup_symbol()) Tim Bird
2011-05-18 21:34 ` Greg KH [this message]
2011-05-19 19:56 ` Jeff Mahoney
2011-05-20 21:29 ` Tim Bird
2011-05-21 14:23 ` Jeff Mahoney
2011-05-18 18:55 ` Alessio Igor Bogani
2011-05-18 19:22 ` your mail Greg KH
2011-05-18 20:35 ` Alessio Igor Bogani
2011-05-18 20:35 ` [PATCH] module: Use binary search in lookup_symbol() Alessio Igor Bogani
2011-05-18 1:07 ` Rusty Russell
2011-05-18 15:26 ` Dirk Behme
2011-05-19 7:26 ` Rusty Russell
2011-05-18 1:10 ` Rusty Russell
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