From: David Marchand <david.marchand@redhat.com>
To: Andrzej Ostruszka <amo@semihalf.com>
Cc: dev <dev@dpdk.org>, Olivier Matz <olivier.matz@6wind.com>,
Konstantin Ananyev <konstantin.ananyev@intel.com>
Subject: Re: [PATCH] ring: optimize corner case for enqueue/dequeue
Date: Sat, 5 Feb 2022 17:48:43 +0100 [thread overview]
Message-ID: <CAJFAV8yWDBpoTd8AF2jvvt6QTAQ5dedZU3d3e8+sZ6x4X_srsQ@mail.gmail.com> (raw)
In-Reply-To: <20220111113739.1104058-1-amo@semihalf.com>
On Tue, Jan 11, 2022 at 12:38 PM Andrzej Ostruszka <amo@semihalf.com> wrote:
> When enqueueing/dequeueing to/from the ring we try to optimize by manual
> loop unrolling. The check for this optimization looks like:
>
> if (likely(idx + n < size)) {
>
> where 'idx' points to the first usable element (empty slot for enqueue,
> data for dequeue). The correct comparison here should be '<=' instead
> of '<'.
>
> This is not a functional error since we fall back to the loop with
> correct checks on indexes. Just a minor suboptimal behaviour for the
> case when we want to enqueue/dequeue exactly the number of elements that
> we have in the ring before wrapping to its beginning.
>
> Fixes: cc4b218790f6 ("ring: support configurable element size")
> Fixes: 286bd05bf70d ("ring: optimisations")
>
> Signed-off-by: Andrzej Ostruszka <amo@semihalf.com>
> Reviewed-by: Olivier Matz <olivier.matz@6wind.com>
> Acked-by: Konstantin Ananyev <konstantin.ananyev@intel.com>
Reviewed-by: Morten Brørup <mb@smartsharesystems.com>
Applied, thanks.
--
David Marchand
prev parent reply other threads:[~2022-02-05 16:49 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-03 14:22 [PATCH 0/1] Minor mistake in ring (en|de)queueing Andrzej Ostruszka
2022-01-03 14:22 ` [PATCH 1/1] ring: fix off by 1 mistake Andrzej Ostruszka
2022-01-03 14:56 ` Morten Brørup
2022-01-06 10:45 ` Olivier Matz
2022-01-10 15:09 ` Ananyev, Konstantin
2022-01-11 11:49 ` Andrzej Ostruszka
2022-01-11 11:37 ` [PATCH] ring: optimize corner case for enqueue/dequeue Andrzej Ostruszka
2022-01-11 12:00 ` Morten Brørup
2022-01-11 13:46 ` Andrzej Ostruszka
2022-01-11 13:53 ` Morten Brørup
2022-02-05 16:48 ` David Marchand [this message]
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