Hi!
> A process can't grab a kernel lock and then switch
> back to user mode, can it?(if it could, I can
> imagine some nasty DoS attacks...)
>
> Problem is, when we decide to schedule in a process
> or not, we know the process was last stuck in
> schedule() ... in kernel mode ;(
>
> I'd lo
It dost seem to me that even when the process is not in the kernel, it
could hold other sorts of fs locks. Also, what if the process is caught in
a signal handler? Couldn't you end up being unable to kill the thing in an
overactive system?
--
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On Thu, 5 Oct 2000, Matti Aarnio wrote:
> On Wed, Oct 04, 2000 at 06:16:57PM -0300, Rik van Riel wrote:
[priority inversion]
> > We don't need that.
> >
> > We just need one boolean per thread ... is it holding a kernel
> > lock or not?
>
> The BKL or *any* (kernel) lock ?
>
>
On Wed, 4 Oct 2000, Rik van Riel wrote:
> On Wed, 4 Oct 2000, LA Walsh wrote:
>
> > I had another thought regarding resource scheduling -- has the
> > idea of a "weightless" process been brought up?
>
> Yes, look for "idle priority", etc..
> It also turned out to have some problems ...
>
> > W
On Wed, Oct 04, 2000 at 06:16:57PM -0300, Rik van Riel wrote:
> > > ---
> > > One way would be to set a flag "I'm holding a lock" and when
> > > it releases the lock(s), deschedule it?
> >
> > There is a well-known name for this -- priority inversion.
> >
> > Implement the whole sheban
On Thu, 5 Oct 2000, Matti Aarnio wrote:
> On Wed, Oct 04, 2000 at 12:49:43PM -0700, LA Walsh wrote:
> > > One problem here is that you might end up with a weightless
> > > process having grabbed a superblock lock, after which a
> > > normal priority CPU hog kicks in and starves the weightless
> >
On Wed, Oct 04, 2000 at 12:49:43PM -0700, LA Walsh wrote:
> > One problem here is that you might end up with a weightless
> > process having grabbed a superblock lock, after which a
> > normal priority CPU hog kicks in and starves the weightless
> > process.
> ---
> One way would be to set a
On Wed, 4 Oct 2000, Nathan Paul Simons wrote:
> On Wed, Oct 04, 2000 at 04:16:22PM -0300, Rik van Riel wrote:
> > Do we have something like an in_kernel(proc) macro ???
>
> "user_mode()" in include/asm/ptrace.h? But that only checks to
> see if the regs struct you passed it are from a kernel thr
On Wed, Oct 04, 2000 at 04:16:22PM -0300, Rik van Riel wrote:
> Do we have something like an in_kernel(proc) macro ???
"user_mode()" in include/asm/ptrace.h? But that only checks to see if
the regs struct you passed it are from a kernel thread or not. No
checks to see if the process has any ke
> One problem here is that you might end up with a weightless
> process having grabbed a superblock lock, after which a
> normal priority CPU hog kicks in and starves the weightless
> process.
---
One way would be to set a flag "I'm holding a lock" and when
it releases the lock(s), desc
On Wed, 4 Oct 2000, LA Walsh wrote:
> I had another thought regarding resource scheduling -- has the
> idea of a "weightless" process been brought up?
Yes, look for "idle priority", etc..
It also turned out to have some problems ...
> Weightless means it doesn't count toward 'load' and the cla
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