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From: Peter Zijlstra <peterz@infradead.org>
To: Nadav Amit <nadav.amit@gmail.com>
Cc: linux-kernel@vger.kernel.org, Andy Lutomirski <luto@kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Nadav Amit <namit@vmware.com>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	Rik van Riel <riel@surriel.com>,
	Josh Poimboeuf <jpoimboe@redhat.com>
Subject: Re: [PATCH v6 1/9] smp: Run functions concurrently in smp_call_function_many_cond()
Date: Mon, 1 Mar 2021 18:10:47 +0100	[thread overview]
Message-ID: <YD0gF9VuqKyVUgVS@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20210220231712.2475218-2-namit@vmware.com>

On Sat, Feb 20, 2021 at 03:17:04PM -0800, Nadav Amit wrote:
> +		/*
> +		 * Choose the most efficient way to send an IPI. Note that the
> +		 * number of CPUs might be zero due to concurrent changes to the
> +		 * provided mask.
> +		 */
> +		if (nr_cpus == 1)
> +			arch_send_call_function_single_ipi(last_cpu);
> +		else if (likely(nr_cpus > 1))
> +			arch_send_call_function_ipi_mask(cfd->cpumask_ipi);

I just ran into conflicts with another patch set, and noticed that the
above should probably be:

		if (nr_cpus == 1)
			send_call_function_single_ipi(last_cpu);
		else if (likely(nr_cpus > 1))
			arch_send_call_function_ipi_mask(cfd->cpumask_ipi);

Which will avoid the IPI when @last_cpu is idle.



  reply	other threads:[~2021-03-01 21:06 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-20 23:17 [PATCH v6 0/9] x86/tlb: Concurrent TLB flushes Nadav Amit
2021-02-20 23:17 ` [PATCH v6 1/9] smp: Run functions concurrently in smp_call_function_many_cond() Nadav Amit
2021-03-01 17:10   ` Peter Zijlstra [this message]
2021-03-01 19:01     ` Nadav Amit
2021-03-02  7:05     ` [PATCH] smp: Micro-optimize smp_call_function_many_cond() Ingo Molnar
2021-03-02  9:54   ` [tip: x86/mm] smp: Run functions concurrently in smp_call_function_many_cond() tip-bot2 for Nadav Amit
2021-03-06 12:12   ` tip-bot2 for Nadav Amit
2021-02-20 23:17 ` [PATCH v6 2/9] x86/mm/tlb: Unify flush_tlb_func_local() and flush_tlb_func_remote() Nadav Amit
2021-03-02  9:54   ` [tip: x86/mm] " tip-bot2 for Nadav Amit
2021-03-06 12:12   ` tip-bot2 for Nadav Amit
2021-02-20 23:17 ` [PATCH v6 3/9] x86/mm/tlb: Open-code on_each_cpu_cond_mask() for tlb_is_not_lazy() Nadav Amit
2021-03-02  9:54   ` [tip: x86/mm] " tip-bot2 for Nadav Amit
2021-03-06 12:12   ` tip-bot2 for Nadav Amit
2021-02-20 23:17 ` [PATCH v6 4/9] x86/mm/tlb: Flush remote and local TLBs concurrently Nadav Amit
2021-03-02  9:54   ` [tip: x86/mm] " tip-bot2 for Nadav Amit
2021-03-06 12:12   ` tip-bot2 for Nadav Amit
2021-02-20 23:17 ` [PATCH v6 5/9] x86/mm/tlb: Privatize cpu_tlbstate Nadav Amit
2021-03-02  9:54   ` [tip: x86/mm] " tip-bot2 for Nadav Amit
2021-03-06 12:12   ` tip-bot2 for Nadav Amit
2021-02-20 23:17 ` [PATCH v6 6/9] x86/mm/tlb: Do not make is_lazy dirty for no reason Nadav Amit
2021-03-02  9:54   ` [tip: x86/mm] " tip-bot2 for Nadav Amit
2021-03-06 12:12   ` tip-bot2 for Nadav Amit
2021-02-20 23:17 ` [PATCH v6 7/9] cpumask: Mark functions as pure Nadav Amit
2021-03-02  9:54   ` [tip: x86/mm] " tip-bot2 for Nadav Amit
2021-03-06 12:12   ` tip-bot2 for Nadav Amit
2021-02-20 23:17 ` [PATCH v6 8/9] x86/mm/tlb: Remove unnecessary uses of the inline keyword Nadav Amit
2021-03-02  9:54   ` [tip: x86/mm] " tip-bot2 for Nadav Amit
2021-03-06 12:12   ` tip-bot2 for Nadav Amit
2021-02-20 23:17 ` [PATCH v6 9/9] smp: inline on_each_cpu_cond() and on_each_cpu() Nadav Amit
2021-03-02  9:54   ` [tip: x86/mm] smp: Inline " tip-bot2 for Nadav Amit
2021-03-06 12:12   ` tip-bot2 for Nadav Amit

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