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From: Michael Ellerman <mpe@ellerman.id.au>
To: Nicholas Piggin <npiggin@gmail.com>,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: linuxppc-dev@lists.ozlabs.org, aneesh.kumar@linux.vnet.ibm.com
Subject: Re: [PATCH 5/6] powerpc/mm: Optimize detection of thread local mm's
Date: Mon, 24 Jul 2017 23:46:44 +1000	[thread overview]
Message-ID: <87h8y2j6bf.fsf@concordia.ellerman.id.au> (raw)
In-Reply-To: <20170724212533.195cb92b@roar.ozlabs.ibm.com>

Nicholas Piggin <npiggin@gmail.com> writes:

> On Mon, 24 Jul 2017 14:28:02 +1000
> Benjamin Herrenschmidt <benh@kernel.crashing.org> wrote:
>
>> Instead of comparing the whole CPU mask every time, let's
>> keep a counter of how many bits are set in the mask. Thus
>> testing for a local mm only requires testing if that counter
>> is 1 and the current CPU bit is set in the mask.
...
>
> Also does it make sense to define it based on NR_CPUS > BITS_PER_LONG?
> If it's <= then it should be similar load and compare, no?

Do we make a machine with that few CPUs? ;)

I don't think it's worth special casing, all the distros run with much
much larger NR_CPUs than that.

cheers

  reply	other threads:[~2017-07-24 13:46 UTC|newest]

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-07-24  4:27 [PATCH 1/6] powerpc/mm: Move pgdir setting into a helper Benjamin Herrenschmidt
2017-07-24  4:27 ` [PATCH 2/6] powerpc/mm: Avoid double irq save/restore in activate_mm Benjamin Herrenschmidt
2017-07-24  4:28 ` [PATCH 3/6] powerpc/mm: Ensure cpumask update is ordered Benjamin Herrenschmidt
2017-07-24 11:20   ` Nicholas Piggin
2017-07-24 20:54     ` Benjamin Herrenschmidt
2017-08-11 11:06     ` Nicholas Piggin
2017-08-11 22:40       ` Benjamin Herrenschmidt
2017-08-17 12:58       ` Michael Ellerman
2017-08-23 12:01   ` [3/6] " Michael Ellerman
2017-07-24  4:28 ` [PATCH 4/6] powerpc/mm: Use mm_is_thread_local() instread of open-coding Benjamin Herrenschmidt
2017-07-24  4:28 ` [PATCH 5/6] powerpc/mm: Optimize detection of thread local mm's Benjamin Herrenschmidt
2017-07-24 11:25   ` Nicholas Piggin
2017-07-24 13:46     ` Michael Ellerman [this message]
2017-07-25  0:34       ` Nicholas Piggin
2017-07-25 12:00         ` Michael Ellerman
2017-07-24 20:58     ` Benjamin Herrenschmidt
2017-07-25  0:44       ` Nicholas Piggin
2017-07-25  1:03         ` Benjamin Herrenschmidt
2017-07-25 10:55           ` Nicholas Piggin
2017-08-04 12:06   ` Frederic Barrat
2017-08-04 12:58     ` Benjamin Herrenschmidt
2017-08-21 17:27   ` Frederic Barrat
2017-08-21 17:35     ` Benjamin Herrenschmidt
2017-08-22 13:18       ` Frederic Barrat
2017-08-22 16:55         ` Benjamin Herrenschmidt
2017-08-24 16:40       ` Frederic Barrat
2017-08-24 18:47         ` Benjamin Herrenschmidt
2017-08-25  4:53           ` Frederic Barrat
2017-08-25  7:44             ` Benjamin Herrenschmidt
2017-08-25  8:03               ` Frederic Barrat
2017-08-22  4:28     ` Michael Ellerman
2017-07-24  4:28 ` [PATCH 6/6] powerpc/mm: Make switch_mm_irqs_off() out of line Benjamin Herrenschmidt
2017-08-24 12:37 ` [1/6] powerpc/mm: Move pgdir setting into a helper Michael Ellerman

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