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 07:05:50 -0800 [thread overview]
Message-ID: <20210107150550.GA12121@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.
Ranges are useful on many systems. Users of systems with insane CPU
enumeration are of course free to provide comma-separated lists of
numbers for their cpumask boot parameters, avoiding use of minus signs.
Thanx, Paul
next prev parent reply other threads:[~2021-01-07 15:06 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
2021-01-07 14:59 ` Peter Zijlstra
2021-01-07 15:32 ` Paul E. McKenney
2021-01-07 15:05 ` Paul E. McKenney [this message]
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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