From: Oleg Nesterov <oleg@redhat.com>
To: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@redhat.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Peter Zijlstra <peterz@infradead.org>, Tejun Heo <tj@kernel.org>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 0/8] Add rcu_sync infrastructure to avoid _expedited() in percpu-rwsem
Date: Wed, 26 Aug 2015 14:16:43 +0200 [thread overview]
Message-ID: <20150826121643.GA10831@redhat.com> (raw)
In-Reply-To: <20150826002220.GZ11078@linux.vnet.ibm.com>
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...
Oleg.
next prev parent reply other threads:[~2015-08-26 12:19 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-08-21 17:42 [PATCH v2 0/8] Add rcu_sync infrastructure to avoid _expedited() in percpu-rwsem Oleg Nesterov
2015-08-21 17:42 ` [PATCH v2 1/8] rcu: Create rcu_sync infrastructure Oleg Nesterov
2015-08-21 17:42 ` [PATCH v2 2/8] rcusync: Introduce struct rcu_sync_ops Oleg Nesterov
2015-08-21 17:42 ` [PATCH v2 3/8] rcusync: Add the CONFIG_PROVE_RCU checks Oleg Nesterov
2015-08-21 17:42 ` [PATCH v2 4/8] rcusync: Introduce rcu_sync_dtor() Oleg Nesterov
2015-08-21 17:42 ` [PATCH v2 5/8] percpu-rwsem: make percpu_free_rwsem() after kzalloc() safe Oleg Nesterov
2015-08-21 17:42 ` [PATCH v2 6/8] percpu-rwsem: change it to rely on rss_sync infrastructure Oleg Nesterov
2015-08-21 17:43 ` [PATCH v2 7/8] percpu-rwsem: fix the comments outdated by rcu_sync Oleg Nesterov
2015-08-21 17:43 ` [PATCH v2 8/8] percpu-rwsem: cleanup the lockdep annotations in percpu_down_read() Oleg Nesterov
2015-08-22 16:38 ` [PATCH v2 0/8] Add rcu_sync infrastructure to avoid _expedited() in percpu-rwsem Paul E. McKenney
2015-08-24 15:34 ` Oleg Nesterov
2015-08-24 18:31 ` parse_args() is too unforgivable? Oleg Nesterov
2015-08-25 1:24 ` Rusty Russell
2015-08-25 15:18 ` [PATCH 0/1] params: don't ignore the rest of cmdline if parse_one() fails Oleg Nesterov
2015-08-25 15:18 ` [PATCH 1/1] " Oleg Nesterov
2015-08-26 0:13 ` Rusty Russell
2015-08-26 0:22 ` [PATCH v2 0/8] Add rcu_sync infrastructure to avoid _expedited() in percpu-rwsem Paul E. McKenney
2015-08-26 12:16 ` Oleg Nesterov [this message]
2015-08-26 12:52 ` Oleg Nesterov
2015-08-26 14:29 ` Paul E. McKenney
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