From: Thomas Gleixner <tglx@linutronix.de>
To: Andi Kleen <andi@firstfloor.org>
Cc: the arch/x86 maintainers <x86@kernel.org>,
KVM <kvm@vger.kernel.org>,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
Peter Zijlstra <peterz@infradead.org>,
Stefano Stabellini <stefano.stabellini@eu.citrix.com>,
Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>,
LKML <linux-kernel@vger.kernel.org>,
Xen Devel <xen-devel@lists.xensource.com>,
Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>,
Avi Kivity <avi@redhat.com>,
Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>,
"H. Peter Anvin" <hpa@zytor.com>,
Attilio Rao <attilio.rao@citrix.com>, Ingo Molnar <mingo@elte.hu>,
Virtualization <virtualization@lists.linux-foundation.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Stephan Diestelhorst <stephan.diestelhorst@amd.com>
Subject: Re: [PATCH RFC V6 0/11] Paravirtualized ticketlocks
Date: Sat, 31 Mar 2012 01:04:41 +0200 (CEST) [thread overview]
Message-ID: <alpine.LFD.2.02.1203310044580.2542@ionos> (raw)
In-Reply-To: <20120330221836.GN17822@one.firstfloor.org>
On Sat, 31 Mar 2012, Andi Kleen wrote:
> > So if a guest exits due to an external event it's easy to inspect the
> > state of that guest and avoid to schedule away when it was interrupted
> > in a spinlock held section. That guest/host shared state needs to be
>
> On a large system under high contention sleeping can perform surprisingly
> well. pthread mutexes have a tendency to beat kernel spinlocks there.
> So avoiding sleeping locks completely (that is what pv locks are
> essentially) is not necessarily that good.
Care to back that up with numbers and proper trace evidence instead of
handwaving?
I've stared at RT traces and throughput problems on _LARGE_ machines
long enough to know what I'm talking about and I can provide evidence
in a split second.
> Your proposal is probably only a good idea on low contention
> and relatively small systems.
Sigh, you have really no fcking clue what you are talking about.
On RT we observed scalabilty problems way before hardware was
available to expose them. So what's your point?
Put up or shut up, really!
tglx
next prev parent reply other threads:[~2012-03-30 23:04 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-03-21 10:20 [PATCH RFC V6 0/11] Paravirtualized ticketlocks Raghavendra K T
2012-03-21 10:20 ` [PATCH RFC V6 1/11] x86/spinlock: replace pv spinlocks with pv ticketlocks Raghavendra K T
2012-03-21 13:04 ` Attilio Rao
2012-03-21 13:22 ` Stephan Diestelhorst
2012-03-21 13:49 ` Attilio Rao
2012-03-21 14:25 ` Stephan Diestelhorst
2012-03-21 14:33 ` Attilio Rao
2012-03-21 14:49 ` Raghavendra K T
2012-03-21 10:21 ` [PATCH RFC V6 2/11] x86/ticketlock: don't inline _spin_unlock when using paravirt spinlocks Raghavendra K T
2012-03-21 17:13 ` Linus Torvalds
2012-03-22 10:06 ` Raghavendra K T
2012-03-21 10:21 ` [PATCH RFC V6 3/11] x86/ticketlock: collapse a layer of functions Raghavendra K T
2012-03-21 10:21 ` [PATCH RFC V6 4/11] xen: defer spinlock setup until boot CPU setup Raghavendra K T
2012-03-21 10:21 ` [PATCH RFC V6 5/11] xen/pvticketlock: Xen implementation for PV ticket locks Raghavendra K T
2012-03-21 10:21 ` [PATCH RFC V6 6/11] xen/pvticketlocks: add xen_nopvspin parameter to disable xen pv ticketlocks Raghavendra K T
2012-03-21 10:21 ` [PATCH RFC V6 7/11] x86/pvticketlock: use callee-save for lock_spinning Raghavendra K T
2012-03-21 10:22 ` [PATCH RFC V6 8/11] x86/pvticketlock: when paravirtualizing ticket locks, increment by 2 Raghavendra K T
2012-03-21 10:22 ` [PATCH RFC V6 9/11] x86/ticketlock: add slowpath logic Raghavendra K T
2012-03-21 10:22 ` [PATCH RFC V6 10/11] xen/pvticketlock: allow interrupts to be enabled while blocking Raghavendra K T
2012-03-21 10:22 ` [PATCH RFC V6 11/11] xen: enable PV ticketlocks on HVM Xen Raghavendra K T
2012-03-26 14:25 ` [PATCH RFC V6 0/11] Paravirtualized ticketlocks Avi Kivity
2012-03-27 7:37 ` Raghavendra K T
2012-03-28 16:09 ` Alan Meadows
2012-03-28 18:21 ` Raghavendra K T
2012-03-29 9:58 ` Avi Kivity
2012-03-29 18:03 ` Raghavendra K T
2012-03-30 10:07 ` Raghavendra K T
2012-04-01 13:18 ` Avi Kivity
2012-04-01 13:48 ` Raghavendra K T
2012-04-01 13:53 ` Avi Kivity
2012-04-01 13:56 ` Raghavendra K T
2012-04-02 9:51 ` Raghavendra K T
2012-04-02 12:15 ` Raghavendra K T
2012-04-05 9:01 ` Avi Kivity
2012-04-05 10:40 ` Raghavendra K T
2012-04-05 8:43 ` Raghavendra K T
2012-03-30 20:26 ` H. Peter Anvin
2012-03-30 22:07 ` Thomas Gleixner
2012-03-30 22:18 ` Andi Kleen
2012-03-30 23:04 ` Thomas Gleixner [this message]
2012-03-31 0:08 ` Andi Kleen
2012-03-31 8:11 ` Ingo Molnar
2012-03-31 4:07 ` Srivatsa Vaddagiri
2012-03-31 4:09 ` Srivatsa Vaddagiri
2012-04-16 15:44 ` Konrad Rzeszutek Wilk
2012-04-16 16:36 ` [Xen-devel] " Ian Campbell
2012-04-16 16:42 ` Jeremy Fitzhardinge
2012-04-17 2:54 ` Srivatsa Vaddagiri
2012-04-01 13:31 ` Avi Kivity
2012-04-02 9:26 ` Thomas Gleixner
2012-04-05 9:15 ` Avi Kivity
2012-04-02 4:36 ` [Xen-devel] " Juergen Gross
2012-04-02 9:42 ` Ian Campbell
2012-04-11 1:29 ` Marcelo Tosatti
2012-03-31 0:51 ` Raghavendra K T
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