From: Stephen Hemminger <stephen@networkplumber.org>
To: Pavan Nikhilesh <pbhagavatula@caviumnetworks.com>
Cc: dev@dpdk.org, cristian.dumitrescu@intel.com
Subject: Re: [dpdk-dev] [PATCH v4 2/3] eal: add u64 bit variant for reciprocal
Date: Tue, 5 Sep 2017 10:29:01 -0700 [thread overview]
Message-ID: <20170905102901.0d9db417@xeon-e3> (raw)
In-Reply-To: <1504608532-18598-2-git-send-email-pbhagavatula@caviumnetworks.com>
On Tue, 5 Sep 2017 16:18:51 +0530
Pavan Nikhilesh <pbhagavatula@caviumnetworks.com> wrote:
> +/**
> + * Unsigned 32-bit divisor structure.
> + */
> +struct rte_reciprocal_u32 {
> uint32_t m;
> uint8_t sh1, sh2;
> -};
> +} __rte_cache_aligned;
> +
> +/**
> + * Unsigned 64-bit divisor structure.
> + */
> +struct rte_reciprocal_u64 {
> + uint64_t m;
> + uint8_t sh1;
> +} __rte_cache_aligned;
I understand you want to squeeze every cycle out but it is not
required that each of these structures always be cache aligned.
They maybe embedded in other structures and having the structure
padded so that these elements are cache aligned would take up
more space and make cache performance worse.
Better off to not put attributes on the structure definitions, and instead
let usages of this feature align where appropriate.
next prev parent reply other threads:[~2017-09-05 17:29 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-09-05 10:48 [dpdk-dev] [PATCH v4 1/3] eal: introduce integer divide through reciprocal Pavan Nikhilesh
2017-09-05 10:48 ` [dpdk-dev] [PATCH v4 2/3] eal: add u64 bit variant for reciprocal Pavan Nikhilesh
2017-09-05 17:29 ` Stephen Hemminger [this message]
2017-09-06 4:32 ` Pavan Nikhilesh Bhagavatula
2017-09-05 10:48 ` [dpdk-dev] [PATCH v4 3/3] test: add tests for reciprocal based division Pavan Nikhilesh
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