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From: Nick Piggin <npiggin@suse.de>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Nick Piggin <npiggin@suse.de>, Jan Beulich <JBeulich@novell.com>,
	Avi Kivity <avi@redhat.com>,
	Xen-devel <xen-devel@lists.xensource.com>
Subject: Re: [PATCH RFC 10/12] x86/pvticketlock: keep count of blocked cpus
Date: Tue, 3 Aug 2010 19:44:51 +1000	[thread overview]
Message-ID: <20100803094451.GA5556@amd> (raw)
In-Reply-To: <1280824360.1923.421.camel@laptop>

On Tue, Aug 03, 2010 at 10:32:40AM +0200, Peter Zijlstra wrote:
> On Fri, 2010-07-16 at 18:03 -0700, Jeremy Fitzhardinge wrote:
> > @@ -26,6 +26,9 @@ typedef struct arch_spinlock {
> >                         __ticket_t head, tail;
> >                 } tickets;
> >         };
> > +#ifdef CONFIG_PARAVIRT_SPINLOCKS
> > +       __ticket_t waiting;
> > +#endif
> >  } arch_spinlock_t; 
> 
> This bloats spinlock_t from u32 to u64 on most distro configs I think,
> since they'll have NR_CPUS=4096 or something large like that and
> probably also want to have this PARAVIRT_SPINLOCKS thing.

Which sucks for carefully packed data structures like dentry.
They'll tend to grow by 8 bytes per spinlock.

  reply	other threads:[~2010-08-03  9:44 UTC|newest]

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-07-17  1:03 [PATCH RFC 00/12] X86 ticket lock cleanups and improvements Jeremy Fitzhardinge
2010-07-17  1:03 ` [PATCH RFC 11/12] x86/pvticketlock: use callee-save for lock_spinning Jeremy Fitzhardinge
2010-07-17  1:03 ` [PATCH RFC 03/12] x86/ticketlock: Use C for __ticket_spin_unlock Jeremy Fitzhardinge
2010-07-20 15:38   ` Konrad Rzeszutek Wilk
2010-07-20 16:17     ` Jeremy Fitzhardinge
2010-08-06 17:47       ` H. Peter Anvin
2010-08-06 20:03         ` Jeremy Fitzhardinge
2010-07-17  1:03 ` [PATCH RFC 07/12] x86/spinlocks: replace pv spinlocks with pv ticketlocks Jeremy Fitzhardinge
2010-07-17  1:03 ` [PATCH RFC 10/12] x86/pvticketlock: keep count of blocked cpus Jeremy Fitzhardinge
2010-08-03  8:32   ` Peter Zijlstra
2010-08-03  9:44     ` Nick Piggin [this message]
2010-08-03 15:45     ` Jeremy Fitzhardinge
2010-07-17  1:03 ` [PATCH RFC 01/12] x86/ticketlock: clean up types and accessors Jeremy Fitzhardinge
2010-07-17  1:03 ` [PATCH RFC 08/12] x86/ticketlock: collapse a layer of functions Jeremy Fitzhardinge
2010-07-17  1:03 ` [PATCH RFC 12/12] x86/pvticketlock: use callee-save for unlock_kick as well Jeremy Fitzhardinge
2010-07-17  1:03 ` [PATCH RFC 06/12] x86/ticketlock: make __ticket_spin_trylock common Jeremy Fitzhardinge
2010-07-17  1:03 ` [PATCH RFC 02/12] x86/ticketlock: convert spin loop to C Jeremy Fitzhardinge
2010-08-02 15:07   ` Peter Zijlstra
2010-08-02 15:17     ` Jeremy Fitzhardinge
2010-08-06 12:43       ` Jan Beulich
2010-08-06 14:53         ` Jeremy Fitzhardinge
2010-08-06 20:17           ` H. Peter Anvin
2010-08-06 20:33             ` Jeremy Fitzhardinge
2010-08-06 21:09               ` H. Peter Anvin
2010-08-06 22:03                 ` Jeremy Fitzhardinge
2010-07-17  1:03 ` [PATCH RFC 04/12] x86/ticketlock: make large and small ticket versions of spin_lock the same Jeremy Fitzhardinge
2010-07-17  1:03 ` [PATCH RFC 05/12] x86/ticketlock: make __ticket_spin_lock common Jeremy Fitzhardinge
2010-07-17  1:03 ` [PATCH RFC 09/12] xen/pvticketlock: Xen implementation for PV ticket locks Jeremy Fitzhardinge
2010-09-26 11:39   ` Srivatsa Vaddagiri
2010-09-26 22:34     ` Jeremy Fitzhardinge
2011-01-18 16:27       ` Srivatsa Vaddagiri
2011-01-19  1:28         ` Jeremy Fitzhardinge
  -- strict thread matches above, loose matches on Subject: below --
2010-07-05 14:53 [PATCH RFC 10/12] x86/pvticketlock: keep count of blocked cpus Jeremy Fitzhardinge

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