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From: "Paul E. McKenney" <paulmck@kernel.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Yury Norov <yury.norov@gmail.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	kernel-team@fb.com, Paul Gortmaker <paul.gortmaker@windriver.com>
Subject: Re: [PATCH RFC cpumask 4/5] cpumask: Add "last" alias for cpu list specifications
Date: Thu, 7 Jan 2021 06:47:57 -0800	[thread overview]
Message-ID: <20210107144757.GK2743@paulmck-ThinkPad-P72> (raw)
In-Reply-To: <X/cYR474/PiTvjfC@hirez.programming.kicks-ass.net>

On Thu, Jan 07, 2021 at 03:18:47PM +0100, Peter Zijlstra wrote:
> On Wed, Jan 06, 2021 at 01:16:50PM -0800, Yury Norov wrote:
> > On Wed, Jan 6, 2021 at 1:50 AM Peter Zijlstra <peterz@infradead.org> wrote:
> 
> > > Aside from the comments Yury made, on how all this is better in
> > > bitmap_parselist(), how about doing s/last/N/ here? For me something
> > > like: "4-N" reads much saner than "4-last".
> > >
> > > Also, it might make sense to teach all this about core/node topology,
> > > but that's going to be messy. Imagine something like "Core1-CoreN" or
> > > "Nore1-NodeN" to mean the mask all/{Core,Node}0.
> > 
> > If you just want to teach bitmap_parselist() to "s/Core0/0-4",  I think
> > it's doable if we add a hook to a proper subsystem in bitmap_parselist().
> > 
> > > And that is another feature that seems to be missing from parselist,
> > > all/except.
> > 
> > We already support groups in a range. I think it partially covers the
> > proposed all/except.
> > 
> > Can you share examples on what you miss?
> 
> The obvious one is the "all/Core0" example above, which would be
> equivalent to "Core1-CoreN".
> 
> Another case that I don't think we can do today is something like, give
> me SMT0 of each core.
> 
> I don't really see the use of the ranges thing, CPU enumeration just
> isn't sane like that. Also, I should really add that randomization pass
> to the CPU enumeration :-)

Please don't!!!

							Thanx, Paul

  reply	other threads:[~2021-01-07 14:48 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-06  0:48 [PATCH RFC cpumask] Allow "all", "none", and "last" in cpumask strings Paul E. McKenney
2021-01-06  0:49 ` [PATCH RFC cpumask 1/5] cpumask: Un-inline cpulist_parse for SMP; prepare for ascii helpers paulmck
2021-01-06  0:49 ` [PATCH RFC cpumask 2/5] cpumask: Make "all" alias global and not just RCU paulmck
2021-01-06  6:32   ` Yury Norov
2021-01-06  0:49 ` [PATCH RFC cpumask 3/5] cpumask: Add a "none" alias to complement "all" paulmck
2021-01-06  6:59   ` Yury Norov
2021-01-06  0:49 ` [PATCH RFC cpumask 4/5] cpumask: Add "last" alias for cpu list specifications paulmck
2021-01-06  8:41   ` Yury Norov
2021-01-06  9:49   ` Peter Zijlstra
2021-01-06 17:45     ` Paul Gortmaker
2021-01-06 21:16     ` Yury Norov
2021-01-07 14:18       ` Peter Zijlstra
2021-01-07 14:47         ` Paul E. McKenney [this message]
2021-01-07 14:59           ` Peter Zijlstra
2021-01-07 15:32             ` Paul E. McKenney
2021-01-07 15:05         ` Paul E. McKenney
2021-01-06  0:49 ` [PATCH RFC cpumask 5/5] rcutorture: Use "all" and "last" in "nohz_full" and "rcu_nocbs" paulmck
2021-01-06  8:49 ` [PATCH RFC cpumask] Allow "all", "none", and "last" in cpumask strings Yury Norov
2021-01-21  7:11   ` Yury Norov
2021-01-21 16:57     ` Paul E. McKenney
2021-01-21 21:39       ` Paul E. McKenney
2021-01-21 22:42     ` Paul Gortmaker

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