linux-kernel - Re: [RFC][PATCH 2/7] smp: Optimize flush_smp_call_function

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Message-ID: <20200528122845.GA551@lenoir>
Date:   Thu, 28 May 2020 14:28:46 +0200
From:   Frederic Weisbecker <frederic@...nel.org>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     tglx@...utronix.de, linux-kernel@...r.kernel.org, x86@...nel.org,
        cai@....pw, mgorman@...hsingularity.net
Subject: Re: [RFC][PATCH 2/7] smp: Optimize flush_smp_call_function_queue()

On Tue, May 26, 2020 at 06:10:59PM +0200, Peter Zijlstra wrote:
> The call_single_queue can contain (two) different callbacks,
> synchronous and asynchronous. The current interrupt handler runs them
> in-order, which means that remote CPUs that are waiting for their
> synchronous call can be delayed by running asynchronous callbacks.
> 
> Rework the interrupt handler to first run the synchonous callbacks.
> 
> Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>

I hope we are not unlucky enough to have dependencies between
some async and sync callbacks that require the whole execution
in order.

Reviewed-by: Frederic Weisbecker <frederic@...nel.org>

(Sweet llist dance, I think I need fresh air and coffee now).