From: Rusty Russell <rusty@rustcorp.com.au>
To: Mike Travis <travis@sgi.com>
Cc: Ingo Molnar <mingo@elte.hu>,
Peter Zijlstra <peterz@infradead.org>,
Andrew Morton <akpm@linux-foundation.org>,
davej@codemonkey.org.uk, David Miller <davem@davemloft.net>,
Eric Dumazet <dada1@cosmosbay.com>,
"Eric W. Biederman" <ebiederm@xmission.com>,
Jack Steiner <steiner@sgi.com>,
Jeremy Fitzhardinge <jeremy@goop.org>, Jes Sorensen <jes@sgi.com>,
"H. Peter Anvin" <hpa@zytor.com>,
Thomas Gleixner <tglx@linutronix.de>,
linux-kernel@vger.kernel.org,
Christoph Lameter <cl@linux-foundation.org>,
Andi Kleen <andi@firstfloor.org>
Subject: Re: [RFC] CPUMASK: proposal for replacing cpumask_t
Date: Fri, 12 Sep 2008 14:55:00 +1000 [thread overview]
Message-ID: <200809121455.02180.rusty@rustcorp.com.au> (raw)
In-Reply-To: <48C84E9E.7080507@sgi.com>
On Thursday 11 September 2008 08:47:58 Mike Travis wrote:
> Here's an initial proposal for abstracting cpumask_t to be either
> an array of 1 or a pointer to an array... Hopefully this will
> minimize the amount of code changes while providing the capabilities
> this change is attempting to do.
>
> Comments most welcome. ;-)
I think this is still "wrong way go back".
I'm yet to be convinced that we really need to allocate cpumasks in any fast
paths. And if not, we should simply allocate them everywhere. I'd rather
see one #ifdef around a place where we can show a perf issue.
Get rid of CPU_MASK_ALL et al in favour of cpu_mask_all. And cpu_mask_any_one
instead of CPU_MASK_CPU0 since that's usually what they want.
API looks like so (look Ma, no typedefs!)
struct cpumask *cpus;
cpus = cpumask_alloc();
if (!cpus)
return -ENOMEM;
cpumask_init_single(cpunum);
OR
cpumask_init(cpu_mask_all);
...
cpumask_free(cpus);
Unmistakable and really hard to screw up. You can even be clever and not
reveal the struct cpumask definition so noone can declare one by accident...
Cheers,
Rusty.
next prev parent reply other threads:[~2008-09-12 4:55 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-09-06 23:50 [RFC 00/13] smp: reduce stack requirements for genapic send_IPI_mask functions Mike Travis
2008-09-06 23:50 ` [RFC 01/13] smp: modify send_IPI_mask interface to accept cpumask_t pointers Mike Travis
2008-09-06 23:50 ` [RFC 02/13] cpumask: add for_each_online_cpu_mask_nr function Mike Travis
2008-09-06 23:50 ` [RFC 03/13] xen: use new " Mike Travis
2008-09-06 23:50 ` [RFC 04/13] cpumask: add cpumask_ptr operations Mike Travis
2008-09-06 23:50 ` [RFC 05/13] cpumask: add get_cpumask_var debug operations Mike Travis
2008-09-06 23:50 ` [RFC 06/13] genapic: use get_cpumask_var operations for allbutself cpumask_ts Mike Travis
2008-09-06 23:50 ` [RFC 07/13] sched: Reduce stack size requirements in kernel/sched.c Mike Travis
2008-09-07 10:24 ` Peter Zijlstra
2008-09-07 11:00 ` Andrew Morton
2008-09-07 13:05 ` Peter Zijlstra
2008-09-08 14:56 ` Mike Travis
2008-09-07 20:28 ` Peter Zijlstra
2008-09-08 14:54 ` Mike Travis
2008-09-08 15:05 ` Peter Zijlstra
2008-09-08 18:38 ` Ingo Molnar
2008-09-10 22:47 ` [RFC] CPUMASK: proposal for replacing cpumask_t Mike Travis
2008-09-10 22:53 ` Andi Kleen
2008-09-10 23:33 ` Mike Travis
2008-09-11 5:21 ` Andi Kleen
2008-09-11 9:00 ` Peter Zijlstra
2008-09-11 15:04 ` Mike Travis
2008-09-12 4:55 ` Rusty Russell [this message]
2008-09-12 14:28 ` Mike Travis
2008-09-12 22:02 ` Rusty Russell
2008-09-12 22:50 ` Mike Travis
2008-09-12 22:58 ` H. Peter Anvin
2008-09-06 23:50 ` [RFC 08/13] cpufreq: Reduce stack size requirements in acpi-cpufreq.c Mike Travis
2008-09-06 23:50 ` [RFC 09/13] genapic: reduce stack pressuge in io_apic.c step 1 temp cpumask_ts Mike Travis
2008-09-08 11:01 ` Andi Kleen
2008-09-08 16:03 ` Mike Travis
2008-09-06 23:50 ` [RFC 10/13] genapic: reduce stack pressuge in io_apic.c step 2 internal abi Mike Travis
2008-09-06 23:50 ` [RFC 11/13] genapic: reduce stack pressuge in io_apic.c step 3 target_cpus Mike Travis
2008-09-07 7:55 ` Bert Wesarg
2008-09-07 9:13 ` Ingo Molnar
2008-09-08 15:01 ` Mike Travis
2008-09-08 15:29 ` Mike Travis
2008-09-06 23:50 ` [RFC 12/13] genapic: reduce stack pressuge in io_apic.c step 4 vector allocation Mike Travis
2008-09-06 23:50 ` [RFC 13/13] genapic: reduce stack pressuge in io_apic.c step 5 cpu_mask_to_apicid Mike Travis
2008-09-07 7:36 ` [RFC 00/13] smp: reduce stack requirements for genapic send_IPI_mask functions Ingo Molnar
2008-09-08 15:17 ` Mike Travis
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