On 08/26, Oleg Nesterov wrote:
>
> On 08/25, Paul E. McKenney wrote:
> >
> > On Mon, Aug 24, 2015 at 05:34:31PM +0200, Oleg Nesterov wrote:
> > >
> > > I booted the kernel with the additional patch below, and nothing bad has
> > > happened, it continues to print
> > >
> > > Writes: Total: 2 Max/Min: 0/0 Fail: 0
> > > Reads : Total: 2 Max/Min: 0/0 Fail: 0
> > >
> > > However, I do not know what this code actually does, so currently I have
> > > no idea if this test makes any sense for percpu_rw_semaphore.
> >
> > Actually, unless I am really confused, that does not look good...
> >
> > I would expect something like this, from a run with rwsem_lock:
> >
> > [ 16.336057] Writes: Total: 473 Max/Min: 0/0 Fail: 0
> > [ 16.337615] Reads : Total: 219 Max/Min: 0/0 Fail: 0
> > [ 31.338152] Writes: Total: 959 Max/Min: 0/0 Fail: 0
> > [ 31.339114] Reads : Total: 437 Max/Min: 0/0 Fail: 0
> > [ 46.340167] Writes: Total: 1365 Max/Min: 0/0 Fail: 0
> > [ 46.341952] Reads : Total: 653 Max/Min: 0/0 Fail: 0
> > [ 61.343027] Writes: Total: 1795 Max/Min: 0/0 Fail: 0
> > [ 61.343968] Reads : Total: 865 Max/Min: 0/0 Fail: 0
> > [ 76.344034] Writes: Total: 2220 Max/Min: 0/0 Fail: 0
> > [ 76.345243] Reads : Total: 1071 Max/Min: 0/0 Fail: 0
> >
> > The "Total" should increase for writes and for reads -- if you are
> > just seeing "Total: 2" over and over, that indicates that either
> > the torture test or rcu_sync got stuck somewhere.
>
> Hmm. I reverted the change in locktorture.c , and I see the same
> numbers when I boot the kernel with
>
> locktorture.verbose=1 locktorture.torture_type=rwsem_lock
>
> parameters.
>
> Writes: Total: 2 Max/Min: 0/0 Fail: 0
> Reads : Total: 2 Max/Min: 0/0 Fail: 0
>
> "Total" doesn't grow. Looks like something is wrong with locktorture.
> I'll try to re-check...
Heh ;) torture threads spin in stutter_wait(). Added another parameter,
locktorture.torture_runnable=1
now I see the similar numbers
Writes: Total: 1242 Max/Min: 0/0 Fail: 0
Reads : Total: 892 Max/Min: 0/0 Fail: 0
Writes: Total: 2485 Max/Min: 0/0 Fail: 0
Reads : Total: 1796 Max/Min: 0/0 Fail: 0
Writes: Total: 3786 Max/Min: 0/0 Fail: 0
Reads : Total: 2713 Max/Min: 0/0 Fail: 0
Writes: Total: 5045 Max/Min: 0/0 Fail: 0
Reads : Total: 3636 Max/Min: 0/0 Fail: 0
with or without s/rw_semaphore/percpu_rw_semaphore/ change in locktorture.c
Oleg.
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