From: Peter Zijlstra <peterz@infradead.org>
To: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: linux-kernel@vger.kernel.org,
Daniel Wagner <daniel.wagner@siemens.com>,
Will Deacon <will.deacon@arm.com>,
x86@kernel.org, Linus Torvalds <torvalds@linux-foundation.org>,
"H. Peter Anvin" <hpa@zytor.com>,
Boqun Feng <boqun.feng@gmail.com>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Subject: Re: [Problem] Cache line starvation
Date: Wed, 26 Sep 2018 09:34:26 +0200 [thread overview]
Message-ID: <20180926073426.GA31905@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20180921120226.6xjgr4oiho22ex75@linutronix.de>
On Fri, Sep 21, 2018 at 02:02:26PM +0200, Sebastian Andrzej Siewior wrote:
> Instrumentation show always the picture:
>
> CPU0 CPU1
> => do_syscall_64 => do_syscall_64
> => SyS_ptrace => syscall_slow_exit_work
> => ptrace_check_attach => ptrace_do_notify / rt_read_unlock
> => wait_task_inactive rt_spin_lock_slowunlock()
> -> while task_running() __rt_mutex_unlock_common()
> / check_task_state() mark_wakeup_next_waiter()
> | raw_spin_lock_irq(&p->pi_lock); raw_spin_lock(¤t->pi_lock);
> | . .
> | raw_spin_unlock_irq(&p->pi_lock); .
> \ cpu_relax() .
> - .
> *IRQ* <lock acquired>
>
> In the error case we observe that the while() loop is repeated more than
> 5000 times which indicates that the pi_lock can be acquired. CPU1 on the
> other side does not make progress waiting for the same lock with interrupts
> disabled.
I've tried really hard to reproduce this in userspace, but so far have
not had any luck. Looks to be a real tricky thing to make happen.
next prev parent reply other threads:[~2018-09-26 7:35 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-21 12:02 [Problem] Cache line starvation Sebastian Andrzej Siewior
2018-09-21 12:13 ` Thomas Gleixner
2018-09-21 12:50 ` Sebastian Andrzej Siewior
2018-09-21 12:20 ` Peter Zijlstra
2018-09-21 12:54 ` Thomas Gleixner
2018-10-03 7:51 ` Catalin Marinas
2018-10-03 8:07 ` Thomas Gleixner
2018-10-03 8:28 ` Peter Zijlstra
2018-10-03 10:43 ` Thomas Gleixner
2018-10-03 8:23 ` Peter Zijlstra
2018-09-26 7:34 ` Peter Zijlstra [this message]
2018-09-26 8:04 ` Thomas Gleixner
2018-09-26 12:53 ` Will Deacon
2018-09-27 14:25 ` Kurt Kanzenbach
2018-09-27 14:41 ` Kurt Kanzenbach
2018-09-27 14:47 ` Thomas Gleixner
2018-09-28 9:05 ` Kurt Kanzenbach
2018-09-28 15:26 ` Kurt Kanzenbach
2018-09-28 19:26 ` Sebastian Andrzej Siewior
2018-09-28 19:34 ` Thomas Gleixner
2018-10-02 6:31 ` Daniel Wagner
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=20180926073426.GA31905@hirez.programming.kicks-ass.net \
--to=peterz@infradead.org \
--cc=bigeasy@linutronix.de \
--cc=boqun.feng@gmail.com \
--cc=daniel.wagner@siemens.com \
--cc=hpa@zytor.com \
--cc=linux-kernel@vger.kernel.org \
--cc=paulmck@linux.vnet.ibm.com \
--cc=torvalds@linux-foundation.org \
--cc=will.deacon@arm.com \
--cc=x86@kernel.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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).