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From: Nick Piggin <nickpiggin@yahoo.com.au>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
	Andrew Morton <akpm@osdl.org>, Linus Torvalds <torvalds@osdl.org>,
	Ingo Molnar <mingo@elte.hu>, Thomas Gleixner <tglx@linutronix.de>,
	Andi Kleen <ak@suse.de>,
	Martin Mares <mj@atrey.karlin.mff.cuni.cz>,
	bjornw@axis.com, schwidefsky@de.ibm.com,
	benedict.gaster@superh.com, lethal@linux-sh.org,
	Chris Zankel <chris@zankel.net>,
	Marc Gauthier <marc@tensilica.com>,
	Joe Taylor <joe@tensilica.com>,
	David Mosberger-Tang <davidm@hpl.hp.com>,
	rth@twiddle.net, spyro@f2s.com, starvik@axis.com,
	tony.luck@intel.com, linux-ia64@vger.kernel.org,
	ralf@linux-mips.org, linux-mips@linux-mips.org,
	grundler@parisc-linux.org, parisc-linux@parisc-linux.org,
	linuxppc-dev@ozlabs.org, paulus@samba.org, linux390@de.ibm.com,
	davem@davemloft.net
Subject: Re: [PATCH 00/05] robust per_cpu allocation for modules
Date: Sat, 15 Apr 2006 05:32:10 +0000	[thread overview]
Message-ID: <4440855A.7040203@yahoo.com.au> (raw)
In-Reply-To: <1145049535.1336.128.camel@localhost.localdomain>

Steven Rostedt wrote:

>  would now create a variable called per_cpu_offset__myint in
> the .data.percpu_offset section.  This variable will point to the (if
> defined in the kernel) __per_cpu_offset[] array.  If this was a module
> variable, it would point to the module per_cpu_offset[] array which is
> created when the modules is loaded.

If I'm following you correctly, this adds another dependent load
to a per-CPU data access, and from memory that isn't node-affine.

If so, I think people with SMP and NUMA kernels would care more
about performance and scalability than the few k of memory this
saves.

-- 
SUSE Labs, Novell Inc.
Send instant messages to your online friends http://au.messenger.yahoo.com 

WARNING: multiple messages have this Message-ID (diff)
From: Nick Piggin <nickpiggin@yahoo.com.au>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
	Andrew Morton <akpm@osdl.org>, Linus Torvalds <torvalds@osdl.org>,
	Ingo Molnar <mingo@elte.hu>, Thomas Gleixner <tglx@linutronix.de>,
	Andi Kleen <ak@suse.de>,
	Martin Mares <mj@atrey.karlin.mff.cuni.cz>,
	bjornw@axis.com, schwidefsky@de.ibm.com,
	benedict.gaster@superh.com, lethal@linux-sh.org,
	Chris Zankel <chris@zankel.net>,
	Marc Gauthier <marc@tensilica.com>,
	Joe Taylor <joe@tensilica.com>,
	David Mosberger-Tang <davidm@hpl.hp.com>,
	rth@twiddle.net, spyro@f2s.com, starvik@axis.com,
	tony.luck@intel.com, linux-ia64@vger.kernel.org,
	ralf@linux-mips.org, linux-mips@linux-mips.org,
	grundler@parisc-linux.org, parisc-linux@parisc-linux.org,
	linuxppc-dev@ozlabs.org, paulus@samba.org, linux390@de.ibm.com,
	davem@davemloft.net
Subject: Re: [PATCH 00/05] robust per_cpu allocation for modules
Date: Sat, 15 Apr 2006 15:32:10 +1000	[thread overview]
Message-ID: <4440855A.7040203@yahoo.com.au> (raw)
In-Reply-To: <1145049535.1336.128.camel@localhost.localdomain>

Steven Rostedt wrote:

>  would now create a variable called per_cpu_offset__myint in
> the .data.percpu_offset section.  This variable will point to the (if
> defined in the kernel) __per_cpu_offset[] array.  If this was a module
> variable, it would point to the module per_cpu_offset[] array which is
> created when the modules is loaded.

If I'm following you correctly, this adds another dependent load
to a per-CPU data access, and from memory that isn't node-affine.

If so, I think people with SMP and NUMA kernels would care more
about performance and scalability than the few k of memory this
saves.

-- 
SUSE Labs, Novell Inc.
Send instant messages to your online friends http://au.messenger.yahoo.com 

WARNING: multiple messages have this Message-ID (diff)
From: Nick Piggin <nickpiggin@yahoo.com.au>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Andrew Morton <akpm@osdl.org>,
	linux-mips@linux-mips.org,
	David Mosberger-Tang <davidm@hpl.hp.com>,
	linux-ia64@vger.kernel.org,
	Martin Mares <mj@atrey.karlin.mff.cuni.cz>,
	spyro@f2s.com, Joe Taylor <joe@tensilica.com>,
	Andi Kleen <ak@suse.de>,
	linuxppc-dev@ozlabs.org, paulus@samba.org,
	benedict.gaster@superh.com, bjornw@axis.com,
	Ingo Molnar <mingo@elte.hu>,
	grundler@parisc-linux.org, starvik@axis.com,
	Linus Torvalds <torvalds@osdl.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	rth@twiddle.net, Chris Zankel <chris@zankel.net>,
	tony.luck@intel.com, LKML <linux-kernel@vger.kernel.org>,
	ralf@linux-mips.org, Marc Gauthier <marc@tensilica.com>,
	lethal@linux-sh.org, schwidefsky@de.ibm.com, linux390@de.ibm.com,
	davem@davemloft.net, parisc-linux@parisc-linux.org
Subject: Re: [PATCH 00/05] robust per_cpu allocation for modules
Date: Sat, 15 Apr 2006 15:32:10 +1000	[thread overview]
Message-ID: <4440855A.7040203@yahoo.com.au> (raw)
In-Reply-To: <1145049535.1336.128.camel@localhost.localdomain>

Steven Rostedt wrote:

>  would now create a variable called per_cpu_offset__myint in
> the .data.percpu_offset section.  This variable will point to the (if
> defined in the kernel) __per_cpu_offset[] array.  If this was a module
> variable, it would point to the module per_cpu_offset[] array which is
> created when the modules is loaded.

If I'm following you correctly, this adds another dependent load
to a per-CPU data access, and from memory that isn't node-affine.

If so, I think people with SMP and NUMA kernels would care more
about performance and scalability than the few k of memory this
saves.

-- 
SUSE Labs, Novell Inc.
Send instant messages to your online friends http://au.messenger.yahoo.com 

  parent reply	other threads:[~2006-04-15  5:32 UTC|newest]

Thread overview: 97+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-04-14 21:18 [PATCH 00/05] robust per_cpu allocation for modules Steven Rostedt
2006-04-14 21:18 ` Steven Rostedt
2006-04-14 21:18 ` Steven Rostedt
2006-04-14 21:18 ` Steven Rostedt
2006-04-14 22:06 ` Andrew Morton
2006-04-14 22:06   ` Andrew Morton
2006-04-14 22:06   ` Andrew Morton
2006-04-14 22:12   ` Steven Rostedt
2006-04-14 22:12     ` Steven Rostedt
2006-04-14 22:12     ` Steven Rostedt
2006-04-14 22:12 ` Chen, Kenneth W
2006-04-14 22:12   ` Chen, Kenneth W
2006-04-14 22:12   ` Chen, Kenneth W
2006-04-14 22:12   ` Chen, Kenneth W
2006-04-14 22:19   ` Steven Rostedt
2006-04-15  3:10 ` [PATCH 00/08] robust per_cpu allocation for modules - V2 Steven Rostedt
2006-04-15  3:10   ` Steven Rostedt
2006-04-15  3:10   ` Steven Rostedt
2006-04-15  5:32 ` Nick Piggin [this message]
2006-04-15  5:32   ` [PATCH 00/05] robust per_cpu allocation for modules Nick Piggin
2006-04-15  5:32   ` Nick Piggin
2006-04-15 20:17   ` Steven Rostedt
2006-04-15 20:17     ` Steven Rostedt
2006-04-15 20:17     ` Steven Rostedt
2006-04-16  2:47     ` Nick Piggin
2006-04-16  2:47       ` Nick Piggin
2006-04-16  2:47       ` Nick Piggin
2006-04-16  3:53       ` Steven Rostedt
2006-04-16  3:53         ` Steven Rostedt
2006-04-16  3:53         ` Steven Rostedt
2006-04-16  7:02         ` Paul Mackerras
2006-04-16  7:02           ` Paul Mackerras
2006-04-16  7:02           ` Paul Mackerras
2006-04-16 13:40           ` Steven Rostedt
2006-04-16 13:40             ` Steven Rostedt
2006-04-16 13:40             ` Steven Rostedt
2006-04-16 13:40             ` Steven Rostedt
2006-04-16 14:03             ` Sam Ravnborg
2006-04-16 14:03               ` Sam Ravnborg
2006-04-16 14:03               ` Sam Ravnborg
2006-04-16 15:34             ` Arnd Bergmann
2006-04-16 15:34               ` Arnd Bergmann
2006-04-16 15:34               ` Arnd Bergmann
2006-04-16 18:03               ` Tony Luck
2006-04-16 18:03                 ` Tony Luck
2006-04-16 18:03                 ` Tony Luck
2006-04-17  0:45               ` Steven Rostedt
2006-04-17  0:45                 ` Steven Rostedt
2006-04-17  0:45                 ` Steven Rostedt
2006-04-17  2:07                 ` Arnd Bergmann
2006-04-17  2:07                   ` Arnd Bergmann
2006-04-17  2:07                   ` Arnd Bergmann
2006-04-17  2:17                   ` Steven Rostedt
2006-04-17  2:17                     ` Steven Rostedt
2006-04-17  2:17                     ` Steven Rostedt
2006-04-17 20:06               ` Ravikiran G Thirumalai
2006-04-17 20:06                 ` Ravikiran G Thirumalai
2006-04-17 20:06                 ` Ravikiran G Thirumalai
2006-04-17  6:47             ` Rusty Russell
2006-04-17  6:47               ` Rusty Russell
2006-04-17  6:47               ` Rusty Russell
2006-04-17 11:33               ` Steven Rostedt
2006-04-17 11:33                 ` Steven Rostedt
2006-04-17 11:33                 ` Steven Rostedt
2006-04-16  7:06         ` Nick Piggin
2006-04-16  7:06           ` Nick Piggin
2006-04-16  7:06           ` Nick Piggin
2006-04-16 16:06           ` Steven Rostedt
2006-04-16 16:06             ` Steven Rostedt
2006-04-16 16:06             ` Steven Rostedt
2006-04-17 17:10           ` Andi Kleen
2006-04-17 17:10             ` Andi Kleen
2006-04-17 17:10             ` Andi Kleen
2006-04-17 16:55   ` Christoph Lameter
2006-04-17 16:55     ` Christoph Lameter
2006-04-17 16:55     ` Christoph Lameter
2006-04-17 22:02     ` Ravikiran G Thirumalai
2006-04-17 22:02       ` Ravikiran G Thirumalai
2006-04-17 22:02       ` Ravikiran G Thirumalai
2006-04-17 23:44       ` Steven Rostedt
2006-04-17 23:44         ` Steven Rostedt
2006-04-17 23:44         ` Steven Rostedt
2006-04-17 23:48         ` Christoph Lameter
2006-04-17 23:48           ` Christoph Lameter
2006-04-17 23:48           ` Christoph Lameter
2006-04-18  1:51           ` Steven Rostedt
2006-04-18  1:51             ` Steven Rostedt
2006-04-18  1:51             ` Steven Rostedt
2006-04-18  6:42         ` Nick Piggin
2006-04-18  6:42           ` Nick Piggin
2006-04-18  6:42           ` Nick Piggin
2006-04-18 12:47           ` Steven Rostedt
2006-04-18 12:47             ` Steven Rostedt
2006-04-18 12:47             ` Steven Rostedt
2006-04-16  6:35 ` Paul Mackerras
2006-04-16  6:35   ` Paul Mackerras
2006-04-16  6:35   ` Paul Mackerras

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