From patchwork Tue Feb 27 05:41:25 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tyler Retzlaff X-Patchwork-Id: 137300 X-Patchwork-Delegate: thomas@monjalon.net Return-Path: X-Original-To: patchwork@inbox.dpdk.org Delivered-To: patchwork@inbox.dpdk.org Received: from mails.dpdk.org (mails.dpdk.org [217.70.189.124]) by inbox.dpdk.org (Postfix) with ESMTP id 64EC443C03; Tue, 27 Feb 2024 06:42:45 +0100 (CET) Received: from mails.dpdk.org (localhost [127.0.0.1]) by mails.dpdk.org (Postfix) with ESMTP id 8C95842E87; Tue, 27 Feb 2024 06:42:19 +0100 (CET) Received: from linux.microsoft.com (linux.microsoft.com [13.77.154.182]) by mails.dpdk.org (Postfix) with ESMTP id 91E3E402A7 for ; Tue, 27 Feb 2024 06:41:42 +0100 (CET) Received: by linux.microsoft.com (Postfix, from userid 1086) id 322E320B74C9; Mon, 26 Feb 2024 21:41:40 -0800 (PST) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 322E320B74C9 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1709012501; bh=KVp3GaPTlA6IhRX2/cqo/lCeuFijymdaCpdHvBKfDFs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=XedJP2uPq9TLkqjdCpGPJjkq4wO58DS6brQkSmKqg0cAke/qSypXd88NaFEsdnM76 onX1YKbBEJ/oExXh5KbNqzletGpHOYI6mHJv25aZNef+ALDnG0cbcwAVwPa7OaWSHl KloPqOTszPOWikswgd59zV7z+5xVMmjK4RgSWYyQ= From: Tyler Retzlaff To: dev@dpdk.org Cc: Ajit Khaparde , Andrew Boyer , Andrew Rybchenko , Bruce Richardson , Chenbo Xia , Chengwen Feng , Dariusz Sosnowski , David Christensen , Hyong Youb Kim , Jerin Jacob , Jie Hai , Jingjing Wu , John Daley , Kevin Laatz , Kiran Kumar K , Konstantin Ananyev , Maciej Czekaj , Matan Azrad , Maxime Coquelin , Nithin Dabilpuram , Ori Kam , Ruifeng Wang , Satha Rao , Somnath Kotur , Suanming Mou , Sunil Kumar Kori , Viacheslav Ovsiienko , Yisen Zhuang , Yuying Zhang , mb@smartsharesystems.com, Tyler Retzlaff Subject: [PATCH v6 09/23] net/i40e: use mbuf descriptor accessors Date: Mon, 26 Feb 2024 21:41:25 -0800 Message-Id: <1709012499-12813-10-git-send-email-roretzla@linux.microsoft.com> X-Mailer: git-send-email 1.8.3.1 In-Reply-To: <1709012499-12813-1-git-send-email-roretzla@linux.microsoft.com> References: <1706657173-26166-1-git-send-email-roretzla@linux.microsoft.com> <1709012499-12813-1-git-send-email-roretzla@linux.microsoft.com> X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org RTE_MARKER typedefs are a GCC extension unsupported by MSVC. Use new rte_mbuf_rearm_data and rte_mbuf_rx_descriptor_fields1 accessors that provide a compatible type pointer without using the marker fields. Use rte_mbuf_prefetch_part2() to prefetch cacheline1 and remove reference to rte marker field. Signed-off-by: Tyler Retzlaff --- drivers/net/i40e/i40e_rxtx_vec_altivec.c | 18 +++++-------- drivers/net/i40e/i40e_rxtx_vec_avx2.c | 34 ++++++------------------- drivers/net/i40e/i40e_rxtx_vec_avx512.c | 35 +++++++------------------- drivers/net/i40e/i40e_rxtx_vec_common.h | 4 +-- drivers/net/i40e/i40e_rxtx_vec_neon.c | 16 ++++++------ drivers/net/i40e/i40e_rxtx_vec_sse.c | 43 +++++++------------------------- 6 files changed, 41 insertions(+), 109 deletions(-) diff --git a/drivers/net/i40e/i40e_rxtx_vec_altivec.c b/drivers/net/i40e/i40e_rxtx_vec_altivec.c index b6b0d38..3e065ee 100644 --- a/drivers/net/i40e/i40e_rxtx_vec_altivec.c +++ b/drivers/net/i40e/i40e_rxtx_vec_altivec.c @@ -55,7 +55,6 @@ /* Initialize the mbufs in vector, process 2 mbufs in one loop */ for (i = 0; i < RTE_I40E_RXQ_REARM_THRESH; i += 2, rxep += 2) { __vector unsigned long vaddr0, vaddr1; - uintptr_t p0, p1; mb0 = rxep[0].mbuf; mb1 = rxep[1].mbuf; @@ -66,10 +65,8 @@ * anyway. So overwrite whole 8 bytes with one load: * 6 bytes of rearm_data plus first 2 bytes of ol_flags. */ - p0 = (uintptr_t)&mb0->rearm_data; - *(uint64_t *)p0 = rxq->mbuf_initializer; - p1 = (uintptr_t)&mb1->rearm_data; - *(uint64_t *)p1 = rxq->mbuf_initializer; + *rte_mbuf_rearm_data(mb0) = rxq->mbuf_initializer; + *rte_mbuf_rearm_data(mb1) = rxq->mbuf_initializer; /* load buf_addr(lo 64bit) and buf_iova(hi 64bit) */ vaddr0 = vec_ld(0, (__vector unsigned long *)&mb0->buf_addr); @@ -370,12 +367,10 @@ /* D.3 copy final 3,4 data to rx_pkts */ vec_st(pkt_mb4, 0, - (__vector unsigned char *)&rx_pkts[pos + 3] - ->rx_descriptor_fields1 + (__vector unsigned char *)rte_mbuf_rx_descriptor_fields1(rx_pkts[pos + 3]) ); vec_st(pkt_mb3, 0, - (__vector unsigned char *)&rx_pkts[pos + 2] - ->rx_descriptor_fields1 + (__vector unsigned char *)rte_mbuf_rx_descriptor_fields1(rx_pkts[pos + 2]) ); /* D.2 pkt 1,2 set in_port/nb_seg and remove crc */ @@ -422,11 +417,10 @@ /* D.3 copy final 1,2 data to rx_pkts */ vec_st(pkt_mb2, 0, - (__vector unsigned char *)&rx_pkts[pos + 1] - ->rx_descriptor_fields1 + (__vector unsigned char *)rte_mbuf_rx_descriptor_fields1(rx_pkts[pos + 1]) ); vec_st(pkt_mb1, 0, - (__vector unsigned char *)&rx_pkts[pos]->rx_descriptor_fields1 + (__vector unsigned char *)rte_mbuf_rx_descriptor_fields1(rx_pkts[pos]) ); desc_to_ptype_v(descs, &rx_pkts[pos], ptype_tbl); desc_to_olflags_v(descs, &rx_pkts[pos]); diff --git a/drivers/net/i40e/i40e_rxtx_vec_avx2.c b/drivers/net/i40e/i40e_rxtx_vec_avx2.c index f468c1f..360d80f 100644 --- a/drivers/net/i40e/i40e_rxtx_vec_avx2.c +++ b/drivers/net/i40e/i40e_rxtx_vec_avx2.c @@ -180,19 +180,6 @@ 0xFF, 0xFF, /* pkt_type set as unknown */ 0xFF, 0xFF /*pkt_type set as unknown */ ); - /* - * compile-time check the above crc and shuffle layout is correct. - * NOTE: the first field (lowest address) is given last in set_epi - * calls above. - */ - RTE_BUILD_BUG_ON(offsetof(struct rte_mbuf, pkt_len) != - offsetof(struct rte_mbuf, rx_descriptor_fields1) + 4); - RTE_BUILD_BUG_ON(offsetof(struct rte_mbuf, data_len) != - offsetof(struct rte_mbuf, rx_descriptor_fields1) + 8); - RTE_BUILD_BUG_ON(offsetof(struct rte_mbuf, vlan_tci) != - offsetof(struct rte_mbuf, rx_descriptor_fields1) + 10); - RTE_BUILD_BUG_ON(offsetof(struct rte_mbuf, hash) != - offsetof(struct rte_mbuf, rx_descriptor_fields1) + 12); /* Status/Error flag masks */ /* @@ -525,11 +512,6 @@ * add in the previously computed rx_descriptor fields to * make a single 256-bit write per mbuf */ - /* check the structure matches expectations */ - RTE_BUILD_BUG_ON(offsetof(struct rte_mbuf, ol_flags) != - offsetof(struct rte_mbuf, rearm_data) + 8); - RTE_BUILD_BUG_ON(offsetof(struct rte_mbuf, rearm_data) != - RTE_ALIGN(offsetof(struct rte_mbuf, rearm_data), 16)); /* build up data and do writes */ __m256i rearm0, rearm1, rearm2, rearm3, rearm4, rearm5, rearm6, rearm7; @@ -543,10 +525,10 @@ rearm2 = _mm256_permute2f128_si256(rearm2, mb2_3, 0x20); rearm0 = _mm256_permute2f128_si256(rearm0, mb0_1, 0x20); /* write to mbuf */ - _mm256_storeu_si256((__m256i *)&rx_pkts[i + 6]->rearm_data, rearm6); - _mm256_storeu_si256((__m256i *)&rx_pkts[i + 4]->rearm_data, rearm4); - _mm256_storeu_si256((__m256i *)&rx_pkts[i + 2]->rearm_data, rearm2); - _mm256_storeu_si256((__m256i *)&rx_pkts[i + 0]->rearm_data, rearm0); + _mm256_storeu_si256((__m256i *)rte_mbuf_rearm_data(rx_pkts[i + 6]), rearm6); + _mm256_storeu_si256((__m256i *)rte_mbuf_rearm_data(rx_pkts[i + 4]), rearm4); + _mm256_storeu_si256((__m256i *)rte_mbuf_rearm_data(rx_pkts[i + 2]), rearm2); + _mm256_storeu_si256((__m256i *)rte_mbuf_rearm_data(rx_pkts[i + 0]), rearm0); /* repeat for the odd mbufs */ const __m256i odd_flags = _mm256_castsi128_si256( @@ -561,10 +543,10 @@ rearm3 = _mm256_blend_epi32(rearm3, mb2_3, 0xF0); rearm1 = _mm256_blend_epi32(rearm1, mb0_1, 0xF0); /* again write to mbufs */ - _mm256_storeu_si256((__m256i *)&rx_pkts[i + 7]->rearm_data, rearm7); - _mm256_storeu_si256((__m256i *)&rx_pkts[i + 5]->rearm_data, rearm5); - _mm256_storeu_si256((__m256i *)&rx_pkts[i + 3]->rearm_data, rearm3); - _mm256_storeu_si256((__m256i *)&rx_pkts[i + 1]->rearm_data, rearm1); + _mm256_storeu_si256((__m256i *)rte_mbuf_rearm_data(rx_pkts[i + 7]), rearm7); + _mm256_storeu_si256((__m256i *)rte_mbuf_rearm_data(rx_pkts[i + 5]), rearm5); + _mm256_storeu_si256((__m256i *)rte_mbuf_rearm_data(rx_pkts[i + 3]), rearm3); + _mm256_storeu_si256((__m256i *)rte_mbuf_rearm_data(rx_pkts[i + 1]), rearm1); /* extract and record EOP bit */ if (split_packet) { diff --git a/drivers/net/i40e/i40e_rxtx_vec_avx512.c b/drivers/net/i40e/i40e_rxtx_vec_avx512.c index f3050cd..e13bd2f 100644 --- a/drivers/net/i40e/i40e_rxtx_vec_avx512.c +++ b/drivers/net/i40e/i40e_rxtx_vec_avx512.c @@ -170,18 +170,6 @@ /* pkt_type set as unknown */ 0xFFFFFFFF ); - /* compile-time check the above crc and shuffle layout is correct. - * NOTE: the first field (lowest address) is given last in set_epi - * calls above. - */ - RTE_BUILD_BUG_ON(offsetof(struct rte_mbuf, pkt_len) != - offsetof(struct rte_mbuf, rx_descriptor_fields1) + 4); - RTE_BUILD_BUG_ON(offsetof(struct rte_mbuf, data_len) != - offsetof(struct rte_mbuf, rx_descriptor_fields1) + 8); - RTE_BUILD_BUG_ON(offsetof(struct rte_mbuf, vlan_tci) != - offsetof(struct rte_mbuf, rx_descriptor_fields1) + 10); - RTE_BUILD_BUG_ON(offsetof(struct rte_mbuf, hash) != - offsetof(struct rte_mbuf, rx_descriptor_fields1) + 12); /* Status/Error flag masks */ /* mask everything except RSS, flow director and VLAN flags @@ -557,11 +545,6 @@ * add in the previously computed rx_descriptor fields to * make a single 256-bit write per mbuf */ - /* check the structure matches expectations */ - RTE_BUILD_BUG_ON(offsetof(struct rte_mbuf, ol_flags) != - offsetof(struct rte_mbuf, rearm_data) + 8); - RTE_BUILD_BUG_ON(offsetof(struct rte_mbuf, rearm_data) != - RTE_ALIGN(offsetof(struct rte_mbuf, rearm_data), 16)); /* build up data and do writes */ __m256i rearm0, rearm1, rearm2, rearm3, rearm4, rearm5, rearm6, rearm7; @@ -580,13 +563,13 @@ rearm0 = _mm256_permute2f128_si256(rearm0, mb0_1, 0x20); /* write to mbuf */ _mm256_storeu_si256 - ((__m256i *)&rx_pkts[i + 6]->rearm_data, rearm6); + ((__m256i *)rte_mbuf_rearm_data(rx_pkts[i + 6]), rearm6); _mm256_storeu_si256 - ((__m256i *)&rx_pkts[i + 4]->rearm_data, rearm4); + ((__m256i *)rte_mbuf_rearm_data(rx_pkts[i + 4]), rearm4); _mm256_storeu_si256 - ((__m256i *)&rx_pkts[i + 2]->rearm_data, rearm2); + ((__m256i *)rte_mbuf_rearm_data(rx_pkts[i + 2]), rearm2); _mm256_storeu_si256 - ((__m256i *)&rx_pkts[i + 0]->rearm_data, rearm0); + ((__m256i *)rte_mbuf_rearm_data(rx_pkts[i + 0]), rearm0); /* repeat for the odd mbufs */ const __m256i odd_flags = _mm256_castsi128_si256 @@ -606,13 +589,13 @@ rearm1 = _mm256_blend_epi32(rearm1, mb0_1, 0xF0); /* again write to mbufs */ _mm256_storeu_si256 - ((__m256i *)&rx_pkts[i + 7]->rearm_data, rearm7); + ((__m256i *)rte_mbuf_rearm_data(rx_pkts[i + 7]), rearm7); _mm256_storeu_si256 - ((__m256i *)&rx_pkts[i + 5]->rearm_data, rearm5); + ((__m256i *)rte_mbuf_rearm_data(rx_pkts[i + 5]), rearm5); _mm256_storeu_si256 - ((__m256i *)&rx_pkts[i + 3]->rearm_data, rearm3); + ((__m256i *)rte_mbuf_rearm_data(rx_pkts[i + 3]), rearm3); _mm256_storeu_si256 - ((__m256i *)&rx_pkts[i + 1]->rearm_data, rearm1); + ((__m256i *)rte_mbuf_rearm_data(rx_pkts[i + 1]), rearm1); /* extract and record EOP bit */ if (split_packet) { @@ -826,7 +809,7 @@ free[0] = m; nb_free = 1; for (i = 1; i < n; i++) { - rte_prefetch0(&txep[i + 3].mbuf->cacheline1); + rte_mbuf_prefetch_part2(txep[i + 3].mbuf); m = rte_pktmbuf_prefree_seg(txep[i].mbuf); if (likely(m)) { if (likely(m->pool == free[0]->pool)) { diff --git a/drivers/net/i40e/i40e_rxtx_vec_common.h b/drivers/net/i40e/i40e_rxtx_vec_common.h index 8b74563..5633268 100644 --- a/drivers/net/i40e/i40e_rxtx_vec_common.h +++ b/drivers/net/i40e/i40e_rxtx_vec_common.h @@ -189,7 +189,6 @@ static inline int i40e_rxq_vec_setup_default(struct i40e_rx_queue *rxq) { - uintptr_t p; struct rte_mbuf mb_def = { .buf_addr = 0 }; /* zeroed mbuf */ mb_def.nb_segs = 1; @@ -199,8 +198,7 @@ /* prevent compiler reordering: rearm_data covers previous fields */ rte_compiler_barrier(); - p = (uintptr_t)&mb_def.rearm_data; - rxq->mbuf_initializer = *(uint64_t *)p; + rxq->mbuf_initializer = *rte_mbuf_rearm_data(&mb_def); rxq->rx_using_sse = 1; return 0; } diff --git a/drivers/net/i40e/i40e_rxtx_vec_neon.c b/drivers/net/i40e/i40e_rxtx_vec_neon.c index d873e30..29dfd92 100644 --- a/drivers/net/i40e/i40e_rxtx_vec_neon.c +++ b/drivers/net/i40e/i40e_rxtx_vec_neon.c @@ -300,10 +300,10 @@ rearm2 = vsetq_lane_u64(vgetq_lane_u32(vlan0, 2), mbuf_init, 1); rearm3 = vsetq_lane_u64(vgetq_lane_u32(vlan0, 3), mbuf_init, 1); - vst1q_u64((uint64_t *)&rx_pkts[0]->rearm_data, rearm0); - vst1q_u64((uint64_t *)&rx_pkts[1]->rearm_data, rearm1); - vst1q_u64((uint64_t *)&rx_pkts[2]->rearm_data, rearm2); - vst1q_u64((uint64_t *)&rx_pkts[3]->rearm_data, rearm3); + vst1q_u64(rte_mbuf_rearm_data(rx_pkts[0]), rearm0); + vst1q_u64(rte_mbuf_rearm_data(rx_pkts[1]), rearm1); + vst1q_u64(rte_mbuf_rearm_data(rx_pkts[2]), rearm2); + vst1q_u64(rte_mbuf_rearm_data(rx_pkts[3]), rearm3); } #define PKTLEN_SHIFT 10 @@ -492,13 +492,13 @@ pkt_mb1 = vreinterpretq_u8_u16(tmp); /* D.3 copy final data to rx_pkts */ - vst1q_u8((void *)&rx_pkts[pos + 3]->rx_descriptor_fields1, + vst1q_u8(rte_mbuf_rx_descriptor_fields1(rx_pkts[pos + 3]), pkt_mb4); - vst1q_u8((void *)&rx_pkts[pos + 2]->rx_descriptor_fields1, + vst1q_u8(rte_mbuf_rx_descriptor_fields1(rx_pkts[pos + 2]), pkt_mb3); - vst1q_u8((void *)&rx_pkts[pos + 1]->rx_descriptor_fields1, + vst1q_u8(rte_mbuf_rx_descriptor_fields1(rx_pkts[pos + 1]), pkt_mb2); - vst1q_u8((void *)&rx_pkts[pos]->rx_descriptor_fields1, + vst1q_u8(rte_mbuf_rx_descriptor_fields1(rx_pkts[pos]), pkt_mb1); desc_to_ptype_v(descs, &rx_pkts[pos], ptype_tbl); diff --git a/drivers/net/i40e/i40e_rxtx_vec_sse.c b/drivers/net/i40e/i40e_rxtx_vec_sse.c index 2d4480a..994c5e1 100644 --- a/drivers/net/i40e/i40e_rxtx_vec_sse.c +++ b/drivers/net/i40e/i40e_rxtx_vec_sse.c @@ -315,14 +315,10 @@ rearm3 = _mm_blend_epi16(mbuf_init, _mm_srli_si128(vlan0, 4), 0x10); /* write the rearm data and the olflags in one write */ - RTE_BUILD_BUG_ON(offsetof(struct rte_mbuf, ol_flags) != - offsetof(struct rte_mbuf, rearm_data) + 8); - RTE_BUILD_BUG_ON(offsetof(struct rte_mbuf, rearm_data) != - RTE_ALIGN(offsetof(struct rte_mbuf, rearm_data), 16)); - _mm_store_si128((__m128i *)&rx_pkts[0]->rearm_data, rearm0); - _mm_store_si128((__m128i *)&rx_pkts[1]->rearm_data, rearm1); - _mm_store_si128((__m128i *)&rx_pkts[2]->rearm_data, rearm2); - _mm_store_si128((__m128i *)&rx_pkts[3]->rearm_data, rearm3); + _mm_store_si128((__m128i *)rte_mbuf_rearm_data(rx_pkts[0]), rearm0); + _mm_store_si128((__m128i *)rte_mbuf_rearm_data(rx_pkts[1]), rearm1); + _mm_store_si128((__m128i *)rte_mbuf_rearm_data(rx_pkts[2]), rearm2); + _mm_store_si128((__m128i *)rte_mbuf_rearm_data(rx_pkts[3]), rearm3); } #define PKTLEN_SHIFT 10 @@ -369,15 +365,7 @@ -rxq->crc_len, /* sub crc on pkt_len */ 0, 0 /* ignore pkt_type field */ ); - /* - * compile-time check the above crc_adjust layout is correct. - * NOTE: the first field (lowest address) is given last in set_epi16 - * call above. - */ - RTE_BUILD_BUG_ON(offsetof(struct rte_mbuf, pkt_len) != - offsetof(struct rte_mbuf, rx_descriptor_fields1) + 4); - RTE_BUILD_BUG_ON(offsetof(struct rte_mbuf, data_len) != - offsetof(struct rte_mbuf, rx_descriptor_fields1) + 8); + __m128i dd_check, eop_check; /* nb_pkts has to be floor-aligned to RTE_I40E_DESCS_PER_LOOP */ @@ -419,19 +407,6 @@ 0xFF, 0xFF, /* pkt_type set as unknown */ 0xFF, 0xFF /*pkt_type set as unknown */ ); - /* - * Compile-time verify the shuffle mask - * NOTE: some field positions already verified above, but duplicated - * here for completeness in case of future modifications. - */ - RTE_BUILD_BUG_ON(offsetof(struct rte_mbuf, pkt_len) != - offsetof(struct rte_mbuf, rx_descriptor_fields1) + 4); - RTE_BUILD_BUG_ON(offsetof(struct rte_mbuf, data_len) != - offsetof(struct rte_mbuf, rx_descriptor_fields1) + 8); - RTE_BUILD_BUG_ON(offsetof(struct rte_mbuf, vlan_tci) != - offsetof(struct rte_mbuf, rx_descriptor_fields1) + 10); - RTE_BUILD_BUG_ON(offsetof(struct rte_mbuf, hash) != - offsetof(struct rte_mbuf, rx_descriptor_fields1) + 12); /* Cache is empty -> need to scan the buffer rings, but first move * the next 'n' mbufs into the cache @@ -535,9 +510,9 @@ staterr = _mm_unpacklo_epi32(sterr_tmp1, sterr_tmp2); /* D.3 copy final 3,4 data to rx_pkts */ - _mm_storeu_si128((void *)&rx_pkts[pos+3]->rx_descriptor_fields1, + _mm_storeu_si128(rte_mbuf_rx_descriptor_fields1(rx_pkts[pos + 3]), pkt_mb4); - _mm_storeu_si128((void *)&rx_pkts[pos+2]->rx_descriptor_fields1, + _mm_storeu_si128(rte_mbuf_rx_descriptor_fields1(rx_pkts[pos + 2]), pkt_mb3); /* D.2 pkt 1,2 set in_port/nb_seg and remove crc */ @@ -571,9 +546,9 @@ staterr = _mm_packs_epi32(staterr, zero); /* D.3 copy final 1,2 data to rx_pkts */ - _mm_storeu_si128((void *)&rx_pkts[pos+1]->rx_descriptor_fields1, + _mm_storeu_si128(rte_mbuf_rx_descriptor_fields1(rx_pkts[pos + 1]), pkt_mb2); - _mm_storeu_si128((void *)&rx_pkts[pos]->rx_descriptor_fields1, + _mm_storeu_si128(rte_mbuf_rx_descriptor_fields1(rx_pkts[pos]), pkt_mb1); desc_to_ptype_v(descs, &rx_pkts[pos], ptype_tbl); /* C.4 calc available number of desc */