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From: Linus Torvalds <torvalds@linux-foundation.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Herbert Xu <herbert@gondor.apana.org.au>,
	Ard Biesheuvel <ardb@kernel.org>,
	LKML <linux-kernel@vger.kernel.org>,
	linux-arch <linux-arch@vger.kernel.org>,
	Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
	Valentin Schneider <valentin.schneider@arm.com>,
	Richard Henderson <rth@twiddle.net>,
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	Jani Nikula <jani.nikula@linux.intel.com>,
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	Rodrigo Vivi <rodrigo.vivi@intel.com>,
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	intel-gfx <intel-gfx@lists.freedesktop.org>,
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	"Paul E. McKenney" <paulmck@kernel.org>,
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	Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
	Lai Jiangshan <jiangshanlai@gmail.com>,
	Shuah Khan <shuah@kernel.org>,
	rcu@vger.kernel.org
Subject: Re: [patch 00/13] preempt: Make preempt count unconditional
Date: Tue, 15 Sep 2020 10:29:50 -0700	[thread overview]
Message-ID: <CAHk-=wg_koVS=8bYurGCZ8zs=zDH5cOKVzFdoj4AkUWEW9mKjA@mail.gmail.com> (raw)
In-Reply-To: <87een35woz.fsf@nanos.tec.linutronix.de>

On Tue, Sep 15, 2020 at 12:24 AM Thomas Gleixner <tglx@linutronix.de> wrote:
>
> Alternatively we just make highmem a bit more expensive by making these
> maps preemptible. RT is doing this for a long time and it's not that
> horrible.

Ack.

In fact, I've wanted to start just removing kmap support entirely. At
some point it's not so much about "I have an old machine that wants
HIGHMEM" but about "I have an old CPU, and I'll just run an old
kernel".

It's not that 32-bit is irrelevant, it's that 32-bit with large
amounts of memory is irrelevant.

Last time this was discussed, iirc the main issue was some
questionable old ARM chips that were still very common in embedded
environments, even with large memory.

But we could definitely start de-emphasizing HIGHMEM.

                     Linus

  reply	other threads:[~2020-09-15 17:47 UTC|newest]

Thread overview: 47+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20200914204209.256266093@linutronix.de>
     [not found] ` <20200914204441.579902354@linutronix.de>
2020-09-15 16:10   ` [patch 06/13] locking/bitspinlock: Clenaup PREEMPT_COUNT leftovers Will Deacon
     [not found] ` <20200914204441.375753691@linutronix.de>
2020-09-15 16:11   ` [patch 04/13] lockdep: " Will Deacon
     [not found] ` <CAHk-=win80rdof8Pb=5k6gT9j_v+hz-TQzKPVastZDvBe9RimQ@mail.gmail.com>
2020-09-15 17:25   ` [patch 00/13] preempt: Make preempt count unconditional Paul E. McKenney
     [not found]   ` <871rj4owfn.fsf@nanos.tec.linutronix.de>
     [not found]     ` <CAHk-=wj0eUuVQ=hRFZv_nY7g5ZLt7Fy3K7SMJL0ZCzniPtsbbg@mail.gmail.com>
     [not found]       ` <CAHk-=wjOV6f_ddg+QVCF6RUe+pXPhSR2WevnNyOs9oT+q2ihEA@mail.gmail.com>
2020-09-15  3:30         ` [PATCH] crypto: lib/chacha20poly1305 - Set SG_MITER_ATOMIC unconditionally Herbert Xu
2020-09-15  6:03           ` Ard Biesheuvel
2020-09-15  6:40             ` Herbert Xu
2020-09-15  6:45           ` Linus Torvalds
2020-09-15  6:55             ` Linus Torvalds
2020-09-15  7:05               ` Herbert Xu
2020-09-15  7:10                 ` Ard Biesheuvel
2020-09-15  9:34                 ` Thomas Gleixner
2020-09-15 10:02                   ` Ard Biesheuvel
2020-09-15 10:05                     ` Herbert Xu
2020-09-15 10:08                       ` Ard Biesheuvel
2020-09-15 10:10                         ` Herbert Xu
2020-09-15 19:04                           ` Thomas Gleixner
2020-09-15  7:08               ` Ard Biesheuvel
2020-09-15  6:20         ` [patch 00/13] preempt: Make preempt count unconditional Ard Biesheuvel
     [not found]           ` <20200915062253.GA26275@gondor.apana.org.au>
2020-09-15  6:39             ` Linus Torvalds
2020-09-15  7:24               ` Thomas Gleixner
2020-09-15 17:29                 ` Linus Torvalds [this message]
2020-09-15  8:39       ` Thomas Gleixner
2020-09-15 17:35         ` Linus Torvalds
2020-09-15 19:57           ` Thomas Gleixner
2020-09-16 18:34             ` Linus Torvalds
2020-09-16  7:37           ` Daniel Vetter
2020-09-16 15:29             ` Paul E. McKenney
2020-09-16 18:32               ` Linus Torvalds
2020-09-16 20:43                 ` Paul E. McKenney
2020-09-17  6:38                 ` Ard Biesheuvel
2020-09-16 20:29               ` Daniel Vetter
2020-09-16 20:58                 ` Paul E. McKenney
2020-09-16 21:43                   ` Daniel Vetter
2020-09-16 22:39                     ` Paul E. McKenney
2020-09-17  7:52                       ` Daniel Vetter
2020-09-17 16:28                         ` Paul E. McKenney
2020-09-29  8:19                     ` Michal Hocko
2020-09-29  8:19                       ` Michal Hocko
2020-09-29  8:20                       ` Michal Hocko
2020-09-29  8:21                       ` Michal Hocko
2020-09-29  8:23                       ` Michal Hocko
2020-09-29  9:00                       ` Daniel Vetter
2020-09-29 14:54                         ` Michal Hocko
2020-09-16 19:23     ` Matthew Wilcox
2020-09-16 20:48       ` Paul E. McKenney
     [not found] ` <20200914204441.268144917@linutronix.de>
2020-09-16 10:56   ` [patch 03/13] preempt: Clenaup PREEMPT_COUNT leftovers Valentin Schneider
     [not found] ` <20200914204441.794954043@linutronix.de>
2020-09-16 10:56   ` [patch 08/13] sched: " Valentin Schneider

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