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From: Stephen Hemminger <stephen@networkplumber.org>
To: Yuanhan Liu <yuanhan.liu@linux.intel.com>
Cc: dev@dpdk.org, Victor Kaplansky <vkaplans@redhat.com>,
	"Michael S. Tsirkin" <mst@redhat.com>
Subject: Re: [dpdk-dev] [PATCH 1/5] vhost: refactor rte_vhost_dequeue_burst
Date: Wed, 2 Dec 2015 23:02:44 -0800	[thread overview]
Message-ID: <20151202230244.5e4ca3fb@xeon-e3> (raw)
In-Reply-To: <1449122773-25510-2-git-send-email-yuanhan.liu@linux.intel.com>

On Thu,  3 Dec 2015 14:06:09 +0800
Yuanhan Liu <yuanhan.liu@linux.intel.com> wrote:

> +#define COPY(dst, src) do {						\
> +	cpy_len = RTE_MIN(desc_avail, mbuf_avail);			\
> +	rte_memcpy((void *)(uintptr_t)(dst),				\
> +		   (const void *)(uintptr_t)(src), cpy_len);		\
> +									\
> +	mbuf_avail  -= cpy_len;						\
> +	mbuf_offset += cpy_len;						\
> +	desc_avail  -= cpy_len;						\
> +	desc_offset += cpy_len;						\
> +} while(0)
> +

I see lots of issues here.

All those void * casts are unnecessary, C casts arguements already.
rte_memcpy is slower for constant size values than memcpy()

This macro violates the rule that ther should be no hidden variables
in a macro. I.e you are assuming cpy_len, desc_avail, and mbuf_avail
are defined in all code using the macro.

Why use an un-typed macro when an inline function would be just
as fast and give type safety?

  reply	other threads:[~2015-12-03  7:02 UTC|newest]

Thread overview: 84+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-12-03  6:06 [dpdk-dev] [PATCH 0/5 for 2.3] vhost rxtx refactor Yuanhan Liu
2015-12-03  6:06 ` [dpdk-dev] [PATCH 1/5] vhost: refactor rte_vhost_dequeue_burst Yuanhan Liu
2015-12-03  7:02   ` Stephen Hemminger [this message]
2015-12-03  7:25     ` Yuanhan Liu
2015-12-03  7:03   ` Stephen Hemminger
2015-12-12  6:55   ` Rich Lane
2015-12-14  1:55     ` Yuanhan Liu
2016-01-26 10:30   ` Xie, Huawei
2016-01-27  3:26     ` Yuanhan Liu
2016-01-27  6:12       ` Xie, Huawei
2016-01-27  6:16         ` Yuanhan Liu
2015-12-03  6:06 ` [dpdk-dev] [PATCH 2/5] vhost: refactor virtio_dev_rx Yuanhan Liu
2015-12-11 20:42   ` Rich Lane
2015-12-14  1:47     ` Yuanhan Liu
2016-01-21 13:50       ` Jérôme Jutteau
2016-01-27  3:27         ` Yuanhan Liu
2015-12-03  6:06 ` [dpdk-dev] [PATCH 3/5] vhost: refactor virtio_dev_merge_rx Yuanhan Liu
2015-12-03  6:06 ` [dpdk-dev] [PATCH 4/5] vhost: do not use rte_memcpy for virtio_hdr copy Yuanhan Liu
2016-01-27  2:46   ` Xie, Huawei
2016-01-27  3:22     ` Yuanhan Liu
2016-01-27  5:56       ` Xie, Huawei
2016-01-27  6:02         ` Yuanhan Liu
2016-01-27  6:16           ` Xie, Huawei
2016-01-27  6:35             ` Yuanhan Liu
2015-12-03  6:06 ` [dpdk-dev] [PATCH 5/5] vhost: don't use unlikely for VIRTIO_NET_F_MRG_RXBUF detection Yuanhan Liu
2016-02-17 22:50 ` [dpdk-dev] [PATCH 0/5 for 2.3] vhost rxtx refactor Thomas Monjalon
2016-02-18  4:09   ` Yuanhan Liu
2016-02-18 13:49 ` [dpdk-dev] [PATCH v2 0/7] " Yuanhan Liu
2016-02-18 13:49   ` [dpdk-dev] [PATCH v2 1/7] vhost: refactor rte_vhost_dequeue_burst Yuanhan Liu
2016-03-03 16:21     ` Xie, Huawei
2016-03-04  2:21       ` Yuanhan Liu
2016-03-07  2:19         ` Xie, Huawei
2016-03-07  2:44           ` Yuanhan Liu
2016-03-03 16:30     ` Xie, Huawei
2016-03-04  2:17       ` Yuanhan Liu
2016-03-07  2:32         ` Xie, Huawei
2016-03-07  2:48           ` Yuanhan Liu
2016-03-07  2:59             ` Xie, Huawei
2016-03-07  6:14               ` Yuanhan Liu
2016-03-03 17:19     ` Xie, Huawei
2016-03-04  2:11       ` Yuanhan Liu
2016-03-07  2:55         ` Xie, Huawei
2016-03-03 17:40     ` Xie, Huawei
2016-03-04  2:32       ` Yuanhan Liu
2016-03-07  3:02         ` Xie, Huawei
2016-03-07  3:03     ` Xie, Huawei
2016-02-18 13:49   ` [dpdk-dev] [PATCH v2 2/7] vhost: refactor virtio_dev_rx Yuanhan Liu
2016-03-07  3:34     ` Xie, Huawei
2016-03-08 12:27       ` Yuanhan Liu
2016-02-18 13:49   ` [dpdk-dev] [PATCH v2 3/7] vhost: refactor virtio_dev_merge_rx Yuanhan Liu
2016-03-07  6:22     ` Xie, Huawei
2016-03-07  6:36       ` Yuanhan Liu
2016-03-07  6:38         ` Xie, Huawei
2016-03-07  6:51           ` Yuanhan Liu
2016-03-07  7:03             ` Xie, Huawei
2016-03-07  7:16               ` Xie, Huawei
2016-03-07  8:20                 ` Yuanhan Liu
2016-03-07  7:52     ` Xie, Huawei
2016-03-07  8:38       ` Yuanhan Liu
2016-03-07  9:27         ` Xie, Huawei
2016-02-18 13:49   ` [dpdk-dev] [PATCH v2 4/7] vhost: do not use rte_memcpy for virtio_hdr copy Yuanhan Liu
2016-03-07  1:20     ` Xie, Huawei
2016-03-07  4:20     ` Stephen Hemminger
2016-03-07  5:24       ` Xie, Huawei
2016-03-07  6:21       ` Yuanhan Liu
2016-02-18 13:49   ` [dpdk-dev] [PATCH v2 5/7] vhost: don't use unlikely for VIRTIO_NET_F_MRG_RXBUF detection Yuanhan Liu
2016-02-18 13:49   ` [dpdk-dev] [PATCH v2 6/7] vhost: do sanity check for desc->len Yuanhan Liu
2016-02-18 13:49   ` [dpdk-dev] [PATCH v2 7/7] vhost: do sanity check for desc->next Yuanhan Liu
2016-03-07  3:10     ` Xie, Huawei
2016-03-07  6:57       ` Yuanhan Liu
2016-02-29 16:06   ` [dpdk-dev] [PATCH v2 0/7] vhost rxtx refactor Thomas Monjalon
2016-03-01  6:01     ` Yuanhan Liu
2016-03-10  4:32   ` [dpdk-dev] [PATCH v3 0/8] vhost rxtx refactor and fixes Yuanhan Liu
2016-03-10  4:32     ` [dpdk-dev] [PATCH v3 1/8] vhost: refactor rte_vhost_dequeue_burst Yuanhan Liu
2016-03-10  4:32     ` [dpdk-dev] [PATCH v3 2/8] vhost: refactor virtio_dev_rx Yuanhan Liu
2016-03-10  4:32     ` [dpdk-dev] [PATCH v3 3/8] vhost: refactor virtio_dev_merge_rx Yuanhan Liu
2016-03-11 16:18       ` Thomas Monjalon
2016-03-14  7:35         ` [dpdk-dev] [PATCH v4 " Yuanhan Liu
2016-03-10  4:32     ` [dpdk-dev] [PATCH v3 4/8] vhost: do not use rte_memcpy for virtio_hdr copy Yuanhan Liu
2016-03-10  4:32     ` [dpdk-dev] [PATCH v3 5/8] vhost: don't use unlikely for VIRTIO_NET_F_MRG_RXBUF detection Yuanhan Liu
2016-03-10  4:32     ` [dpdk-dev] [PATCH v3 6/8] vhost: do sanity check for desc->len Yuanhan Liu
2016-03-10  4:32     ` [dpdk-dev] [PATCH v3 7/8] vhost: do sanity check for desc->next against with vq->size Yuanhan Liu
2016-03-10  4:32     ` [dpdk-dev] [PATCH v3 8/8] vhost: avoid dead loop chain Yuanhan Liu
2016-03-14 23:09     ` [dpdk-dev] [PATCH v3 0/8] vhost rxtx refactor and fixes Thomas Monjalon

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