From: Stephen Hemminger <stephen@networkplumber.org>
To: Joyce Kong <joyce.kong@arm.com>
Cc: maxime.coquelin@redhat.com, tiwei.bie@intel.com,
zhihong.wang@intel.com, thomas@monjalon.net, jerinj@marvell.com,
yinan.wang@intel.com, honnappa.nagarahalli@arm.com,
gavin.hu@arm.com, nd@arm.com, dev@dpdk.org
Subject: Re: [dpdk-dev] [PATCH v2 1/2] virtio: one way barrier for split vring used idx
Date: Thu, 2 Apr 2020 08:47:56 -0700 [thread overview]
Message-ID: <20200402084756.2dc243ae@hermes.lan> (raw)
In-Reply-To: <20200402025753.31420-2-joyce.kong@arm.com>
On Thu, 2 Apr 2020 10:57:52 +0800
Joyce Kong <joyce.kong@arm.com> wrote:
> - (vq)->vq_used_cons_idx))
> +static inline uint16_t
> +virtqueue_nused(struct virtqueue *vq)
vq is unmodified and should be const
> +{
> + uint16_t idx;
> + if (vq->hw->weak_barriers) {
Put blank line between declaration and if statement
> +/* x86 prefers to using rte_smp_rmb over __atomic_load_n as it reports
> + * a slightly better perf, which comes from the saved branch by the compiler.
> + * The if and else branches are identical with the smp and cio barriers both
> + * defined as compiler barriers on x86.
> + */
Do not put comments on left margin (except in function prolog).
> +#ifdef RTE_ARCH_X86_64
> + idx = vq->vq_split.ring.used->idx;
> + rte_smp_rmb();
> +#else
> + idx = __atomic_load_n(&(vq)->vq_split.ring.used->idx,
> + __ATOMIC_ACQUIRE);
> +#endif
> + } else {
> + idx = vq->vq_split.ring.used->idx;
> + rte_cio_rmb();
> + }
> + return (idx - vq->vq_used_cons_idx);
Parenthesis around arguments to return are unnecessary.
BSD code likes it, Linux style does not.
> +}
This kind of arch specific code is hard to maintain.
Does it really make that much difference.
next prev parent reply other threads:[~2020-04-02 15:48 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-12 9:24 [dpdk-dev] [PATCH v1 0/2] one way barrier for split vring idx Joyce Kong
2020-02-12 9:24 ` [dpdk-dev] [PATCH v1 1/2] virtio: one way barrier for split vring used idx Joyce Kong
2020-02-12 9:24 ` [dpdk-dev] [PATCH v1 2/2] virtio: one way barrier for split vring avail idx Joyce Kong
2020-04-02 2:57 ` [dpdk-dev] [PATCH v2 0/2] one way barrier for split vring idx Joyce Kong
2020-04-02 2:57 ` [dpdk-dev] [PATCH v2 1/2] virtio: one way barrier for split vring used idx Joyce Kong
2020-04-02 15:47 ` Stephen Hemminger [this message]
2020-04-03 8:55 ` Gavin Hu
2020-04-16 4:40 ` Honnappa Nagarahalli
2020-04-16 6:46 ` Joyce Kong
2020-04-02 2:57 ` [dpdk-dev] [PATCH v2 2/2] virtio: one way barrier for split vring avail idx Joyce Kong
2020-04-06 15:26 ` [dpdk-dev] [PATCH v3 0/2] one way barrier for split vring idx Joyce Kong
2020-04-16 9:08 ` Ye Xiaolong
2020-04-06 15:26 ` [dpdk-dev] [PATCH v3 1/2] virtio: one way barrier for split vring used idx Joyce Kong
2020-04-17 6:51 ` Ye Xiaolong
2020-04-17 8:14 ` Joyce Kong
2020-04-06 15:26 ` [dpdk-dev] [PATCH v3 2/2] virtio: one way barrier for split vring avail idx Joyce Kong
2020-04-24 3:39 ` [dpdk-dev] [PATCH v4 0/2] one way barrier for split vring idx Joyce Kong
2020-04-28 16:06 ` Maxime Coquelin
2020-04-29 17:45 ` Ferruh Yigit
2020-04-30 9:09 ` Maxime Coquelin
2020-04-30 9:16 ` Joyce Kong
2020-04-30 9:24 ` Maxime Coquelin
2020-04-24 3:39 ` [dpdk-dev] [PATCH v4 1/2] virtio: one way barrier for split vring used idx Joyce Kong
2020-04-27 9:03 ` Maxime Coquelin
2020-04-24 3:39 ` [dpdk-dev] [PATCH v4 2/2] virtio: one way barrier for split vring avail idx Joyce Kong
2020-04-27 9:03 ` Maxime Coquelin
2020-04-30 9:14 ` [dpdk-dev] [PATCH v5 0/2] one way barrier for split vring idx Joyce Kong
2020-04-30 20:54 ` Maxime Coquelin
2020-04-30 9:14 ` [dpdk-dev] [PATCH v5 1/2] virtio: one way barrier for split vring used idx Joyce Kong
2020-04-30 22:58 ` Ferruh Yigit
2020-05-04 10:04 ` Maxime Coquelin
2020-04-30 9:14 ` [dpdk-dev] [PATCH v5 2/2] virtio: one way barrier for split vring avail idx Joyce Kong
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