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From: Peter Zijlstra <peterz@infradead.org>
To: Nicholas Piggin <npiggin@gmail.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
	"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
	Ingo Molnar <mingo@redhat.com>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	linux-arch <linux-arch@vger.kernel.org>,
	Avi Kivity <avi@scylladb.com>,
	maged michael <maged.michael@gmail.com>,
	Boqun Feng <boqun.feng@gmail.com>,
	Dave Watson <davejwatson@fb.com>,
	Will Deacon <will.deacon@arm.com>,
	linux-kernel <linux-kernel@vger.kernel.org>,
	Andrew Hunter <ahh@google.com>, Paul Mackerras <paulus@samba.org>,
	Andy Lutomirski <luto@kernel.org>,
	Alan Stern <stern@rowland.harvard.edu>,
	linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
	gromer <gromer@google.com>
Subject: Re: [PATCH v4 for 4.14 1/3] membarrier: Provide register expedited private command
Date: Fri, 29 Sep 2017 13:45:18 +0200	[thread overview]
Message-ID: <20170929114518.gtr7v7sf4oskjuut@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20170929213853.46c4675b@roar.ozlabs.ibm.com>

On Fri, Sep 29, 2017 at 09:38:53PM +1000, Nicholas Piggin wrote:

> Not really. There is some ability to hold onto a line for a time, but
> there is no way to starve them, let alone starve hundreds of other
> CPUs. They will request the cacheline exclusive and eventually get it.

OK, hardware fairness there is nice.

> I would really prefer to go this way on powerpc first. We could add the
> the registration APIs as basically no-ops, but which would allow the
> locking approach to be changed if we find it causes issues. I'll try to
> find some time and a big system when I can.

Fair enough I suppose.

> > A semi related issue; I suppose we can do a arch upcall to flush_tlb_mm
> > and reset the mm_cpumask when we change cpuset groups.
> 
> For powerpc we have been looking at how mm_cpumask can be improved.
> It has real drawbacks even when you don't consider this new syscall.

What else do you use mm_cpumask for?

      reply	other threads:[~2017-09-29 11:45 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-09-26 17:51 [PATCH v4 for 4.14 1/3] membarrier: Provide register expedited private command Mathieu Desnoyers
2017-09-26 17:51 ` [PATCH for 4.14 2/3] membarrier: selftest: Test private expedited cmd Mathieu Desnoyers
2017-09-26 19:41   ` Shuah Khan
2017-09-26 19:55     ` Mathieu Desnoyers
2017-09-26 20:08       ` Shuah Khan
2017-09-26 20:15         ` Mathieu Desnoyers
2017-09-26 20:34           ` Shuah Khan
2017-09-26 21:15           ` Greg Kroah-Hartman
2017-09-26 21:15             ` Greg Kroah-Hartman
2017-09-26 17:51 ` [PATCH v4 for 4.14 3/3] membarrier: Document scheduler barrier requirements Mathieu Desnoyers
2017-09-26 20:46   ` Mathieu Desnoyers
2017-09-26 20:43 ` [PATCH v4 for 4.14 1/3] membarrier: Provide register expedited private command Mathieu Desnoyers
2017-09-27 13:04   ` Nicholas Piggin
2017-09-28 13:31     ` Mathieu Desnoyers
2017-09-28 15:01       ` Nicholas Piggin
2017-09-28 15:29         ` Mathieu Desnoyers
2017-09-28 16:16           ` Nicholas Piggin
2017-09-28 18:28             ` Mathieu Desnoyers
2017-09-28 15:51         ` Peter Zijlstra
2017-09-28 16:27           ` Nicholas Piggin
2017-09-29 10:31             ` Peter Zijlstra
2017-09-29 11:38               ` Nicholas Piggin
2017-09-29 11:45                 ` Peter Zijlstra [this message]

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