From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: Chuyi Zhou <zhouchuyi@bytedance.com>
Cc: tglx@linutronix.de, mingo@redhat.com, luto@kernel.org,
peterz@infradead.org, paulmck@kernel.org, muchun.song@linux.dev,
bp@alien8.de, dave.hansen@linux.intel.com, pbonzini@redhat.com,
clrkwllms@kernel.org, rostedt@goodmis.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3 04/12] smp: Use on-stack cpumask in smp_call_function_many_cond
Date: Wed, 18 Mar 2026 16:55:52 +0100 [thread overview]
Message-ID: <20260318155552.41ffiYbB@linutronix.de> (raw)
In-Reply-To: <20260318045638.1572777-5-zhouchuyi@bytedance.com>
On 2026-03-18 12:56:30 [+0800], Chuyi Zhou wrote:
> This patch use on-stack cpumask to replace percpu cfd cpumask in
> smp_call_function_many_cond(). Note that when both CONFIG_CPUMASK_OFFSTACK
> and PREEMPT_RT are enabled, allocation during preempt-disabled section
> would break RT. Therefore, only do this when CONFIG_CPUMASK_OFFSTACK=n.
> This is a preparation for enabling preemption during csd_lock_wait() in
> smp_call_function_many_cond().
You explained why we do this only for !CONFIG_CPUMASK_OFFSTACK but
failed to explain why we need a function local cpumask. Other than
preparation step. But this allocation looks pointless, let me look
further…
> Signed-off-by: Chuyi Zhou <zhouchuyi@bytedance.com>
> Reviewed-by: Muchun Song <muchun.song@linux.dev>
Sebastian
next prev parent reply other threads:[~2026-03-18 15:55 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-18 4:56 [PATCH v3 00/12] Allow preemption during IPI completion waiting to improve real-time performance Chuyi Zhou
2026-03-18 4:56 ` [PATCH v3 01/12] smp: Disable preemption explicitly in __csd_lock_wait Chuyi Zhou
2026-03-18 14:13 ` Steven Rostedt
2026-03-18 4:56 ` [PATCH v3 02/12] smp: Enable preemption early in smp_call_function_single Chuyi Zhou
2026-03-18 14:14 ` Steven Rostedt
2026-03-19 2:30 ` Chuyi Zhou
2026-03-18 4:56 ` [PATCH v3 03/12] smp: Remove get_cpu from smp_call_function_any Chuyi Zhou
2026-03-18 14:32 ` Steven Rostedt
2026-03-18 15:39 ` Sebastian Andrzej Siewior
2026-03-18 4:56 ` [PATCH v3 04/12] smp: Use on-stack cpumask in smp_call_function_many_cond Chuyi Zhou
2026-03-18 14:38 ` Steven Rostedt
2026-03-18 15:55 ` Sebastian Andrzej Siewior [this message]
2026-03-19 3:02 ` Chuyi Zhou
2026-03-18 4:56 ` [PATCH v3 05/12] smp: Free call_function_data via RCU in smpcfd_dead_cpu Chuyi Zhou
2026-03-18 16:19 ` Sebastian Andrzej Siewior
2026-03-19 7:48 ` Chuyi Zhou
2026-03-18 4:56 ` [PATCH v3 06/12] smp: Enable preemption early in smp_call_function_many_cond Chuyi Zhou
2026-03-18 16:55 ` Sebastian Andrzej Siewior
2026-03-19 3:46 ` Chuyi Zhou
2026-03-18 4:56 ` [PATCH v3 07/12] smp: Remove preempt_disable from smp_call_function Chuyi Zhou
2026-03-18 4:56 ` [PATCH v3 08/12] smp: Remove preempt_disable from on_each_cpu_cond_mask Chuyi Zhou
2026-03-18 4:56 ` [PATCH v3 09/12] scftorture: Remove preempt_disable in scftorture_invoke_one Chuyi Zhou
2026-03-18 4:56 ` [PATCH v3 10/12] x86/mm: Move flush_tlb_info back to the stack Chuyi Zhou
2026-03-18 17:21 ` Sebastian Andrzej Siewior
2026-03-18 20:24 ` Nadav Amit
2026-03-18 22:28 ` Nadav Amit
2026-03-19 8:49 ` Sebastian Andrzej Siewior
2026-03-19 10:37 ` Nadav Amit
2026-03-19 10:58 ` Sebastian Andrzej Siewior
2026-03-19 13:41 ` Chuyi Zhou
2026-03-19 14:40 ` Sebastian Andrzej Siewior
2026-03-20 14:33 ` Chuyi Zhou
2026-03-18 4:56 ` [PATCH v3 11/12] x86/mm: Enable preemption during native_flush_tlb_multi Chuyi Zhou
2026-03-18 4:56 ` [PATCH v3 12/12] x86/mm: Enable preemption during flush_tlb_kernel_range Chuyi Zhou
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