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Re: using bootchart

On Wed, Dec 06, 2006 at 07:42:29PM -0500, Kevin Mark wrote:
> On Wed, Dec 06, 2006 at 09:34:09AM +0800, Yuwen Dai wrote:
> > Dear all,
> > 
> > When I used bootchart to benchmark booting of Debian sarge, I found S40hotplug
> > took nearly 15 seconds.  S40hotplug calls {pci,usb,isapnp}.rc, and installing
> > some modules.  Is there any way to reduce this time? Thanks in advance.
> > 
> > Best regards,
> Hi Dai Yuwen,
> from my estimation, hotplug is used to detect hardware and then install
> kernel modules for them. So, if you use a kernel that includes all the
> modules, then they dont need to be loaded by hotplug. Thus this should
> make hotplug do nothing and make it shorter.

FWIW, I've have a situation where hotplug spent several seconds
figuring out that everything was either already loaded or was
unneccessary for the operation of the system (this was on my
knoppmyth box). as a result, I was able to turn off hotplug altogether
and shave quite a bit of time off my boot. Of course, that means I
can't just plug in a USB key, but no great loss on that 
box. Having a quicker boot time is worth the trade-off. 

watch your hotplug as it boots and see what its really doing for you,
maybe not much, and if you don't need it, you can safely turn it
off. (ymmv). or you can replace it by hard-coding the modules you need
into a startup file and at least wipe out the time it spends figuring
out what to load.

ymmv greatly.


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