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Subject: RE: [PATCH] examples/l3fwd: add option to set RX burst size
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To: "Jie Hai" <haijie1@huawei.com>, <dev@dpdk.org>, <thomas@monjalon.net>,
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> From: Jie Hai [mailto:haijie1@huawei.com]
> Sent: Saturday, 12 October 2024 10.41
>=20
> Now the Rx burst size is fixed to MAX_PKT_BURST (32). This
> parameter needs to be modified in some performance optimization
> scenarios. So an option '--burst' is added to set the burst size
> explicitly. The default value is DEFAULT_PKT_BURST (32) and maximum
> value is MAX_PKT_BURST (512).

Good idea.

>=20
> Signed-off-by: Jie Hai <haijie1@huawei.com>
> ---
>=20
> -#define MAX_PKT_BURST     32
> +#define DEFAULT_PKT_BURST 32
> +#define MAX_PKT_BURST 512
>  #define BURST_TX_DRAIN_US 100 /* TX drain every ~100us */
>=20
>  #define MEMPOOL_CACHE_SIZE 256

It seems strange to use a burst size larger than the mempool cache size.

You might want to make the cache size configurable too, or simply define =
MEMPOOL_CACHE_SIZE as RTE_MEMPOOL_CACHE_MAX_SIZE (currently 512) instead =
of 256.

And, as a safety measure, consider adding:
#include <assert.h>
static_assert(MEMPOOL_CACHE_SIZE >=3D MAX_PKT_BURST);