Re: Kernel thoughts of a Linux user

Gerold J. Wucherpfennig
2004-11-22T18:30:07Z

On Sunday 21 November 2004 19:29, you wrote:
> 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.

I'm a stupid idiot, but I'm sure that the sysfs and hal thing still has to
mature for a few years. Just imagine such things like listing all
available modem devices. Listing /sys/class/tty/*/dev without
the virtual consoles just isn't enough.

Regards,
Gerold

>
> > > 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