From: Torsten Duwe <duwe@lst.de>
To: Raghavendra KT <raghavendra.kt.linux@gmail.com>
Cc: Tom Musta <tommusta@gmail.com>,
Peter Zijlstra <peterz@infradead.org>,
Raghavendra KT <raghavendra.kt@linux.vnet.ibm.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Paul Mackerras <paulus@samba.org>,
Anton Blanchard <anton@samba.org>,
Scott Wood <scottwood@freescale.com>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
linuxppc-dev@lists.ozlabs.org, Ingo Molnar <mingo@kernel.org>
Subject: Re: [PATCH v2] powerpc ticket locks
Date: Tue, 11 Feb 2014 11:40:30 +0100 [thread overview]
Message-ID: <20140211104030.GG2107@lst.de> (raw)
In-Reply-To: <CAC4Lta2Pssu5QY_QLmy5C3Fm2G3fwpiuc5BNOLBnQTmmRH+W4Q@mail.gmail.com>
On Tue, Feb 11, 2014 at 03:23:51PM +0530, Raghavendra KT wrote:
> How much important to have holder information for PPC? From my
> previous experiment
> on x86, it was lock-waiter preemption which is problematic rather than
> lock-holder preemption.
It's something very special to IBM pSeries: the hypervisor can assign
fractions of physical CPUs to guests. Sometimes a guest with 4 quarter
CPUs will be faster than 1 monoprocessor. (correct me if I'm wrong).
The directed yield resolves the silly situation when holder and waiter
reside on the same physical CPU, as I understand it.
x86 has nothing comparable.
Torsten
WARNING: multiple messages have this Message-ID (diff)
From: Torsten Duwe <duwe@lst.de>
To: Raghavendra KT <raghavendra.kt.linux@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Paul Mackerras <paulus@samba.org>,
Anton Blanchard <anton@samba.org>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
Peter Zijlstra <peterz@infradead.org>,
Scott Wood <scottwood@freescale.com>,
Tom Musta <tommusta@gmail.com>, Ingo Molnar <mingo@kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
linuxppc-dev@lists.ozlabs.org,
Raghavendra KT <raghavendra.kt@linux.vnet.ibm.com>
Subject: Re: [PATCH v2] powerpc ticket locks
Date: Tue, 11 Feb 2014 11:40:30 +0100 [thread overview]
Message-ID: <20140211104030.GG2107@lst.de> (raw)
In-Reply-To: <CAC4Lta2Pssu5QY_QLmy5C3Fm2G3fwpiuc5BNOLBnQTmmRH+W4Q@mail.gmail.com>
On Tue, Feb 11, 2014 at 03:23:51PM +0530, Raghavendra KT wrote:
> How much important to have holder information for PPC? From my
> previous experiment
> on x86, it was lock-waiter preemption which is problematic rather than
> lock-holder preemption.
It's something very special to IBM pSeries: the hypervisor can assign
fractions of physical CPUs to guests. Sometimes a guest with 4 quarter
CPUs will be faster than 1 monoprocessor. (correct me if I'm wrong).
The directed yield resolves the silly situation when holder and waiter
reside on the same physical CPU, as I understand it.
x86 has nothing comparable.
Torsten
next prev parent reply other threads:[~2014-02-11 10:40 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-02-07 16:58 [PATCH v2] powerpc ticket locks Torsten Duwe
2014-02-07 16:58 ` Torsten Duwe
2014-02-07 17:12 ` Peter Zijlstra
2014-02-07 17:12 ` Peter Zijlstra
2014-02-07 17:55 ` Torsten Duwe
2014-02-07 17:55 ` Torsten Duwe
2014-02-10 3:10 ` Benjamin Herrenschmidt
2014-02-10 3:10 ` Benjamin Herrenschmidt
2014-02-10 15:52 ` Torsten Duwe
2014-02-10 15:52 ` Torsten Duwe
2014-02-10 17:53 ` Peter Zijlstra
2014-02-10 17:53 ` Peter Zijlstra
2014-02-11 2:44 ` Benjamin Herrenschmidt
2014-02-11 2:44 ` Benjamin Herrenschmidt
2014-02-11 2:56 ` Al Viro
2014-02-11 2:56 ` Al Viro
2014-02-11 3:38 ` Benjamin Herrenschmidt
2014-02-11 3:38 ` Benjamin Herrenschmidt
2014-02-11 9:53 ` Raghavendra KT
2014-02-11 9:53 ` Raghavendra KT
2014-02-11 10:40 ` Torsten Duwe [this message]
2014-02-11 10:40 ` Torsten Duwe
2014-02-11 18:30 ` Scott Wood
2014-02-11 18:30 ` Scott Wood
2014-02-11 19:34 ` Benjamin Herrenschmidt
2014-02-11 19:34 ` Benjamin Herrenschmidt
2014-02-11 9:39 ` Raghavendra KT
2014-02-11 9:39 ` Raghavendra KT
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