Re: Kernel thoughts of a Linux user

Greg KH
2004-11-21T18:30:20Z

On Sat, Nov 20, 2004 at 11:31:12AM +0100, Gerold J. Wucherpfennig wrote:
> > On Thu, Nov 18, 2004 at 06:59:27PM +0100, Gerold J. Wucherpfennig wrote:
> > >
> > > - Make sysfs optional and enable to publish kernel <-> userspace data
> > > especially the kernel's KObject data across the kernel's netlink interface
> as
> > > it has been summarized on www.kerneltrap.org. This will avoid the
> > > deadlocks sysfs does introduce when some userspace app holds an open file
> > > handle of an sysfs object (KObject) which is to be removed. An importrant
> side
> > > effect for embedded systems will be that the RAM overhead introduced by
> sysfs
> > > will vaporize.
> >
> > What RAM overhead? With 2.6.10-rc2 the memory footprint of sysfs has
> > been drasticly shrunk.
>
> Sorry I my kernel knowledge only consists of kerneltrap.org news :-(
> I didn't knew that.

Please research things before claiming they are a problem.

> > What deadlocks are you referring to?
>
> I don't know if it are deadlocks, please read last years article from lwn:
> http://lwn.net/Articles/36850/

My word, that's a year and a half old article. Do you really think that
we would have not fixed this issue by now? Again, please do a semblance
of research before claiming there are problems in today's kernels.

> > And the netlink interface for hotplug events is already present in the
> > latest kernel.
>
> I don't know much about netlink. But sysfs --> libsysfs --> hal --> dbus
> seems to be a lot of an overhead. Maybe create an in-kernel queue
> for hardware information requests and publish the hardware information
> with netlink would be a little less overhead??? Just a though...

Again, please do a bit of research. This is not how HAL or the hotplug
interfaces work today.

Not to be rude, but again, if you had spent a little ammount of time
looing into the claims you were making, you would have found out that
they were false.

greg k-h