[EXT] Re: [v1 04/10] bus/dpaa: optimize bman acquire/release

[Jun Yang]

Hi,
> +     rte_memcpy(bm_bufs, mcr->acquire.bufs,
> +             sizeof(struct bm_buffer) * rst);
"mcr->acquire.bufs" is located in register space, it is supposed to improve performance to copy it to DDR(bm_bufs) to parse and read.

BR
Jun

-----Original Message-----
From: Stephen Hemminger <stephen at networkplumber.org> 
Sent: Wednesday, May 28, 2025 10:31 PM
To: Vanshika Shukla <vanshika.shukla at nxp.com>
Cc: dev at dpdk.org; Hemant Agrawal <hemant.agrawal at nxp.com>; Sachin Saxena <sachin.saxena at nxp.com>; Jun Yang <jun.yang at nxp.com>
Subject: [EXT] Re: [v1 04/10] bus/dpaa: optimize bman acquire/release

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On Wed, 28 May 2025 16:09:28 +0530
vanshika.shukla at nxp.com wrote:

> +RTE_EXPORT_INTERNAL_SYMBOL(bman_acquire_fast)
> +int
> +bman_acquire_fast(struct bman_pool *pool, uint64_t *bufs, uint8_t 
> +num) {
> +     struct bman_portal *p = get_affine_portal();
> +     struct bm_mc_command *mcc;
> +     struct bm_mc_result *mcr;
> +     uint8_t i, rst;
> +     struct bm_hw_buf_desc bm_bufs[FSL_BM_BURST_MAX];
> +
> +#ifdef RTE_LIBRTE_DPAA_HWDEBUG
> +     if (!num || (num > FSL_BM_BURST_MAX))
> +             return -EINVAL;
> +     if (pool->params.flags & BMAN_POOL_FLAG_ONLY_RELEASE)
> +             return -EINVAL;
> +#endif
> +
> +     mcc = bm_mc_start(&p->p);
> +     mcc->acquire.bpid = pool->params.bpid;
> +     bm_mc_commit(&p->p, BM_MCC_VERB_CMD_ACQUIRE |
> +                     (num & BM_MCC_VERB_ACQUIRE_BUFCOUNT));
> +     while (!(mcr = bm_mc_result(&p->p)))
> +             ;
> +     rst = mcr->verb & BM_MCR_VERB_ACQUIRE_BUFCOUNT;
> +     if (unlikely(!rst))
> +             return 0;
> +
> +     rte_memcpy(bm_bufs, mcr->acquire.bufs,
> +             sizeof(struct bm_buffer) * rst);
> +
> +     for (i = 0; i < rst; i++)
> +             bufs[i] = bman_hw_extract_addr(&bm_bufs[i]);
> +

Why do you need multiple the local copy?
Does hw_extract_addr modify the buffers?