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 14:52:15 +0200 [thread overview]
Message-ID: <20150826125215.GA25142@redhat.com> (raw)
In-Reply-To: <20150826121643.GA10831@redhat.com>
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.
next prev parent reply other threads:[~2015-08-26 12:54 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
2015-08-26 12:52 ` Oleg Nesterov [this message]
2015-08-26 14:29 ` Paul E. McKenney
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20150826125215.GA25142@redhat.com \
--to=oleg@redhat.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@redhat.com \
--cc=paulmck@linux.vnet.ibm.com \
--cc=peterz@infradead.org \
--cc=tj@kernel.org \
--cc=torvalds@linux-foundation.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.