From: Shrikanth Hegde <sshegde@linux.ibm.com>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>,
Gabriele Monaco <gmonaco@redhat.com>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Michael Jeanson <mjeanson@efficios.com>,
Jens Axboe <axboe@kernel.dk>,
"Paul E. McKenney" <paulmck@kernel.org>,
"Gautham R. Shenoy" <gautham.shenoy@amd.com>,
Florian Weimer <fweimer@redhat.com>,
Tim Chen <tim.c.chen@intel.com>,
Yury Norov <yury.norov@gmail.com>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [patch V3 07/20] cpumask: Introduce cpumask_weighted_or()
Date: Mon, 3 Nov 2025 14:45:33 +0530 [thread overview]
Message-ID: <88d397b7-5eeb-41eb-ba44-980e72008fd2@linux.ibm.com> (raw)
In-Reply-To: <20251029124515.717519165@linutronix.de>
On 10/29/25 6:39 PM, Thomas Gleixner wrote:
> CID management OR's two cpumasks and then calculates the weight on the
> result. That's inefficient as that has to walk the same stuff twice. As
> this is done with runqueue lock held, there is a real benefit of speeding
> this up. Depending on the system this results in 10-20% less cycles spent
> with runqueue lock held for a 4K cpumask.
>
> Provide cpumask_weighted_or() and the corresponding bitmap functions which
> return the weight of the OR result right away.
>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> Reviewed-by: Yury Norov (NVIDIA) <yury.norov@gmail.com>
> ---
> V3: Rename again - Yury
> V2: Rename and use the BITMAP_WEIGHT() macro - Yury
> ---
> include/linux/bitmap.h | 15 +++++++++++++++
> include/linux/cpumask.h | 16 ++++++++++++++++
> lib/bitmap.c | 6 ++++++
> 3 files changed, 37 insertions(+)
>
> /**
> + * cpumask_weighted_or - *dstp = *src1p | *src2p and return the weight of the result
> + * @dstp: the cpumask result
> + * @src1p: the first input
> + * @src2p: the second input
> + *
> + * Return: The number of bits set in the resulting cpumask @dstp
> + */
> +static __always_inline
> +unsigned int cpumask_weighted_or(struct cpumask *dstp, const struct cpumask *src1p,
> + const struct cpumask *src2p)
> +{
> + return bitmap_weighted_or(cpumask_bits(dstp), cpumask_bits(src1p),
> + cpumask_bits(src2p), small_cpumask_bits);
> +}
nit:
We have currently cpumask_weight_and & variants.
Wouldn't it be better to name it cpumask_weight_or ?
next prev parent reply other threads:[~2025-11-03 9:15 UTC|newest]
Thread overview: 65+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-10-29 13:08 [patch V3 00/20] sched: Rewrite MM CID management Thomas Gleixner
2025-10-29 13:08 ` [patch V3 01/20] sched/mmcid: Revert the complex " Thomas Gleixner
2025-10-29 13:08 ` [patch V3 02/20] sched/mmcid: Use proper data structures Thomas Gleixner
2025-10-29 15:31 ` Mathieu Desnoyers
2025-10-29 13:08 ` [patch V3 03/20] sched/mmcid: Cacheline align MM CID storage Thomas Gleixner
2025-10-29 15:39 ` Mathieu Desnoyers
2025-10-29 21:09 ` Thomas Gleixner
2025-10-30 14:15 ` Mathieu Desnoyers
2025-10-29 13:09 ` [patch V3 04/20] sched: Fixup whitespace damage Thomas Gleixner
2025-10-29 15:42 ` Mathieu Desnoyers
2025-10-29 21:11 ` Thomas Gleixner
2025-10-29 13:09 ` [patch V3 05/20] sched/mmcid: Move scheduler code out of global header Thomas Gleixner
2025-10-29 15:43 ` Mathieu Desnoyers
2025-10-29 13:09 ` [patch V3 06/20] sched/mmcid: Prevent pointless work in mm_update_cpus_allowed() Thomas Gleixner
2025-10-29 15:45 ` Mathieu Desnoyers
2025-10-29 13:09 ` [patch V3 07/20] cpumask: Introduce cpumask_weighted_or() Thomas Gleixner
2025-10-29 15:49 ` Mathieu Desnoyers
2025-11-03 9:15 ` Shrikanth Hegde [this message]
2025-11-03 13:29 ` Thomas Gleixner
2025-11-10 16:11 ` Peter Zijlstra
2025-11-10 16:42 ` Mathieu Desnoyers
2025-10-29 13:09 ` [patch V3 08/20] sched/mmcid: Use cpumask_weighted_or() Thomas Gleixner
2025-10-29 15:51 ` Mathieu Desnoyers
2025-10-29 13:09 ` [patch V3 09/20] cpumask: Cache num_possible_cpus() Thomas Gleixner
2025-10-29 15:54 ` Mathieu Desnoyers
2025-10-29 21:11 ` Thomas Gleixner
2025-11-01 22:59 ` Thomas Gleixner
2025-11-03 10:06 ` Shrikanth Hegde
2025-11-03 13:28 ` Thomas Gleixner
2025-10-29 13:09 ` [patch V3 10/20] sched/mmcid: Convert mm CID mask to a bitmap Thomas Gleixner
2025-10-30 13:59 ` Mathieu Desnoyers
2025-10-29 13:09 ` [patch V3 11/20] signal: Move MMCID exit out of sighand lock Thomas Gleixner
2025-10-29 13:09 ` [patch V3 12/20] sched/mmcid: Move initialization out of line Thomas Gleixner
2025-10-30 14:02 ` Mathieu Desnoyers
2025-10-29 13:09 ` [patch V3 13/20] sched/mmcid: Provide precomputed maximal value Thomas Gleixner
2025-10-30 14:23 ` Mathieu Desnoyers
2025-10-31 15:06 ` Thomas Gleixner
2025-10-31 15:14 ` Mathieu Desnoyers
2025-10-29 13:09 ` [patch V3 14/20] sched/mmcid: Serialize sched_mm_cid_fork()/exit() with a mutex Thomas Gleixner
2025-10-30 14:25 ` Mathieu Desnoyers
2025-10-29 13:09 ` [patch V3 15/20] sched/mmcid: Introduce per task/CPU ownership infrastrcuture Thomas Gleixner
2025-10-30 14:45 ` Mathieu Desnoyers
2025-10-29 13:09 ` [patch V3 16/20] sched/mmcid: Provide new scheduler CID mechanism Thomas Gleixner
2025-10-30 15:09 ` Mathieu Desnoyers
2025-10-29 13:09 ` [patch V3 17/20] sched/mmcid: Provide CID ownership mode fixup functions Thomas Gleixner
2025-10-30 15:51 ` Mathieu Desnoyers
2025-10-31 16:54 ` Thomas Gleixner
2025-10-31 19:15 ` Mathieu Desnoyers
2025-10-29 13:09 ` [patch V3 18/20] irqwork: Move data struct to a types header Thomas Gleixner
2025-10-30 15:52 ` Mathieu Desnoyers
2025-10-29 13:09 ` [patch V3 19/20] sched/mmcid: Implement deferred mode change Thomas Gleixner
2025-10-30 15:56 ` Mathieu Desnoyers
2025-10-29 13:09 ` [patch V3 20/20] sched/mmcid: Switch over to the new mechanism Thomas Gleixner
2025-10-30 16:07 ` Mathieu Desnoyers
2025-10-31 16:57 ` Thomas Gleixner
2025-10-31 19:17 ` Mathieu Desnoyers
2025-11-24 12:10 ` Mark Brown
2025-11-24 12:27 ` Florian Weimer
2025-11-24 13:28 ` Mark Brown
2025-10-30 5:00 ` [patch V3 00/20] sched: Rewrite MM CID management Shrikanth Hegde
2025-10-30 6:40 ` Shrikanth Hegde
2025-10-31 19:36 ` Thomas Gleixner
2025-11-01 7:56 ` Shrikanth Hegde
2025-11-01 12:27 ` Thomas Gleixner
2025-11-10 17:09 ` Gabriele Monaco
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