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Date:   Tue, 30 May 2023 08:27:48 +0100
Message-ID: <87pm6ijn2j.wl-maz@kernel.org>
From:   Marc Zyngier <maz@kernel.org>
To:     "Liao, Chang" <liaochang1@huawei.com>
Cc:     Shanker Donthineni <sdonthineni@nvidia.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
        Michael Walle <michael@walle.cc>,
        <linux-kernel@vger.kernel.org>, Vikram Sethi <vsethi@nvidia.com>,
        Jason Sequeira <jsequeira@nvidia.com>
Subject: Re: [PATCH v5 1/3] genirq: Use hlist for managing resend handlers
In-Reply-To: <5eea1d90-a903-d211-9dd7-38cd824c1573@huawei.com>
References: <20230519134902.1495562-1-sdonthineni@nvidia.com>
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        <6dc6642a-1e7c-f111-1fa2-be54826ecef6@huawei.com>
        <86cz2jcykv.wl-maz@kernel.org>
        <5eea1d90-a903-d211-9dd7-38cd824c1573@huawei.com>
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On Tue, 30 May 2023 02:44:05 +0100,
"Liao, Chang" <liaochang1@huawei.com> wrote:
> 
> >> What is the benefit of using hlist here? If you want to enjoy the
> >> low latency of querying elements by key, you must define a hlist table
> >> with a reasonable number of buckets. Otherwise, I don't think the time
> >> complexity of hlist is better than a regular double-linked list, right?
> > 
> > You do realise that the list is processed in order, one element after
> > the other, without ever querying any arbitrary element? Have you read
> > the code?
> 
> Yes, so i *wonder* why not use regular a linked-list here if no need to do
> arbitrary querying. I have no doubt the idea of these changes are sound,
> just curious about the data structure used to maintain resend IRQs.

What about it? For the use case at hand, they result in the same
complexity. Unless you have spotted a corner case that results in a
non O(1) complexity?

	M.

-- 
Without deviation from the norm, progress is not possible.