From: Nicholas Piggin <npiggin@gmail.com>
To: Michael Ellerman <mpe@ellerman.id.au>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
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: Tue, 25 Jul 2017 10:34:39 +1000 [thread overview]
Message-ID: <20170725103439.5a8851b5@roar.ozlabs.ibm.com> (raw)
In-Reply-To: <87h8y2j6bf.fsf@concordia.ellerman.id.au>
On Mon, 24 Jul 2017 23:46:44 +1000
Michael Ellerman <mpe@ellerman.id.au> wrote:
> 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.
Not further special-casing, but just casing it based on NR_CPUS
rather than BOOK3S.
Thanks,
Nick
next prev parent reply other threads:[~2017-07-25 0:34 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
2017-07-25 0:34 ` Nicholas Piggin [this message]
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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