On Wed, Aug 26, 2015 at 02:52:15PM +0200, Oleg Nesterov wrote:
> 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
Whew!!! ;-)
Thanx, Paul
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
