From: Yury Norov <yury.norov@gmail.com>
To: paulmck@kernel.org
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
kernel-team@fb.com, Paul Gortmaker <paul.gortmaker@windriver.com>
Subject: Re: [PATCH RFC cpumask 2/5] cpumask: Make "all" alias global and not just RCU
Date: Tue, 5 Jan 2021 22:32:51 -0800 [thread overview]
Message-ID: <CAAH8bW_euakp=vSKcZoH4=6WHuAuEH-4LdKm21C=-+4jdrT8xQ@mail.gmail.com> (raw)
In-Reply-To: <20210106004956.11961-2-paulmck@kernel.org>
Hi Paul,
On Tue, Jan 5, 2021 at 4:49 PM <paulmck@kernel.org> wrote:
>
> From: Paul Gortmaker <paul.gortmaker@windriver.com>
>
> It is probably better that we don't have subsystem specific
> abbreviations or aliases for generic CPU list specifications.
>
> Hence we move the "all" from RCU out to lib/ so that it can be
> used in any instance where CPU lists are being parsed.
>
> Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
> ---
> Documentation/admin-guide/kernel-parameters.rst | 7 +++++++
> Documentation/admin-guide/kernel-parameters.txt | 4 +---
> kernel/rcu/tree_plugin.h | 13 ++++---------
> lib/cpumask.c | 6 ++++++
> 4 files changed, 18 insertions(+), 12 deletions(-)
>
> diff --git a/Documentation/admin-guide/kernel-parameters.rst b/Documentation/admin-guide/kernel-parameters.rst
> index 06fb1b4..cdf4e81 100644
> --- a/Documentation/admin-guide/kernel-parameters.rst
> +++ b/Documentation/admin-guide/kernel-parameters.rst
> @@ -68,6 +68,13 @@ For example one can add to the command line following parameter:
>
> where the final item represents CPUs 100,101,125,126,150,151,...
>
> +The following convenience aliases are also accepted and used:
> +
> + foo_cpus=all
> +
> +is equivalent to "foo_cpus=0-N" -- where "N" is the numerically last CPU on
> +the system, thus avoiding looking up the value in "/sys/devices/system/cpu"
> +in advance on each deployed system.
>
>
> This document may not be entirely up to date and comprehensive. The command
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index c722ec1..0f4379b 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -4037,9 +4037,7 @@
> see CONFIG_RAS_CEC help text.
>
> rcu_nocbs= [KNL]
> - The argument is a cpu list, as described above,
> - except that the string "all" can be used to
> - specify every CPU on the system.
> + The argument is a cpu list, as described above.
>
> In kernels built with CONFIG_RCU_NOCB_CPU=y, set
> the specified list of CPUs to be no-callback CPUs.
> diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
> index 7e291ce..642ebd6 100644
> --- a/kernel/rcu/tree_plugin.h
> +++ b/kernel/rcu/tree_plugin.h
> @@ -1463,20 +1463,15 @@ static void rcu_cleanup_after_idle(void)
>
> /*
> * Parse the boot-time rcu_nocb_mask CPU list from the kernel parameters.
> - * The string after the "rcu_nocbs=" is either "all" for all CPUs, or a
> - * comma-separated list of CPUs and/or CPU ranges. If an invalid list is
> - * given, a warning is emitted and all CPUs are offloaded.
> + * If the list is invalid, a warning is emitted and all CPUs are offloaded.
> */
> static int __init rcu_nocb_setup(char *str)
> {
> alloc_bootmem_cpumask_var(&rcu_nocb_mask);
> - if (!strcasecmp(str, "all"))
> + if (cpulist_parse(str, rcu_nocb_mask)) {
> + pr_warn("rcu_nocbs= bad CPU range, all CPUs set\n");
> cpumask_setall(rcu_nocb_mask);
> - else
> - if (cpulist_parse(str, rcu_nocb_mask)) {
> - pr_warn("rcu_nocbs= bad CPU range, all CPUs set\n");
> - cpumask_setall(rcu_nocb_mask);
> - }
> + }
> return 1;
> }
> __setup("rcu_nocbs=", rcu_nocb_setup);
> diff --git a/lib/cpumask.c b/lib/cpumask.c
> index 6e6e835..9f8ff72 100644
> --- a/lib/cpumask.c
> +++ b/lib/cpumask.c
> @@ -2,6 +2,7 @@
> #include <linux/slab.h>
> #include <linux/kernel.h>
> #include <linux/bitops.h>
> +#include <linux/string.h>
> #include <linux/cpumask.h>
> #include <linux/export.h>
> #include <linux/memblock.h>
> @@ -104,6 +105,11 @@ EXPORT_SYMBOL(cpumask_next_wrap);
> */
> int cpulist_parse(const char *buf, struct cpumask *dstp)
> {
> + if (!strcmp(buf, "all")) {
> + cpumask_setall(dstp);
> + return 0;
> + }
I like the extensions. Can you move this chunk inside bitmap_parselist()
to let other users like nodelist_parse() use it?
> return bitmap_parselist(buf, cpumask_bits(dstp), nr_cpumask_bits);
> }
> EXPORT_SYMBOL(cpulist_parse);
> --
> 2.9.5
>
next prev parent reply other threads:[~2021-01-06 6:33 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 [this message]
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
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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