calc_tx_descs(9)

💅 calc_tx_descs(9) — Kernel API Manual, but make it make sense

okay so bestie, welcome to calc_tx_descs(9) from the Kernel API Manual 🌸 this one is short and sweet, and honestly? it's giving "tiny function, big responsibilities" energy. let's get into it ✨

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✨ NAME ✨

calc_tx_descs — calculate the number of Tx descriptors for a packet 💫

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🎀 SYNOPSIS 🎀

unsigned int calc_tx_descs (const struct sk_buff *skb );

like, that's the whole vibe. one function, one argument, one unsigned int coming back at you 🫶

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🌸 ARGUMENTS 🌸

• skb — the packet 👑 that's it. that's the argument. it's the packet, bestie.

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🦋 DESCRIPTION 🦋

so what does it actually do? it returns the number of Tx descriptors needed for the given Ethernet packet 💅 no cap.

and here's the little detail you gotta remember: Ethernet packets require addition of WR and CPL headers. so yeah — the descriptor math has to account for that, periodt 🔥

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⭐ SEE ALSO ⭐

okay this list is long, and we are not skipping a single one of these, because every reference ate and left no crumbs 👑

Kernel file ./drivers/net/ethernet/chelsio/cxgb3/sge.c — and then, in order:

• refill_rspq(9)
• need_skb_unmap(9)
• unmap_skb(9)
• free_tx_desc(9)
• reclaim_completed_tx(9)
• should_restart_tx(9)
• free_rx_bufs(9)
• add_one_rx_buf(9)
• refill_fl(9)
• recycle_rx_buf(9)
• alloc_ring(9)
• t3_reset_qset(9)
• t3_free_qset(9)
• init_qset_cntxt(9)
• sgl_len(9)
• flits_to_desc(9)
• get_packet(9)
• get_packet_pg(9)
• get_imm_packet(9)
• write_sgl(9)
• check_ring_tx_db(9)
• write_wr_hdr_sgl(9)
• write_tx_pkt_wr(9)
• t3_eth_xmit(9)
• write_imm(9)
• check_desc_avail(9)
• reclaim_completed_tx_imm(9)
• ctrl_xmit(9)
• restart_ctrlq(9)
• deferred_unmap_destructor(9)
• write_ofld_wr(9)
• calc_tx_descs_ofld(9)
• ofld_xmit(9)
• restart_offloadq(9)
• queue_set(9)
• is_ctrl_pkt(9)
• t3_offload_tx(9)
• offload_enqueue(9)
• deliver_partial_bundle(9)
• ofld_poll(9)
• rx_offload(9)
• restart_tx(9)
• cxgb3_arp_process(9)
• rx_eth(9)
• lro_add_page(9)
• handle_rsp_cntrl_info(9)
• check_ring_db(9)
• is_new_response(9)
• process_responses(9)
• napi_rx_handler(9)
• process_pure_responses(9)
• handle_responses(9)
• t3_intr_handler(9)
• t3_sge_err_intr_handler(9)
• sge_timer_tx(9)
• sge_timer_rx(9)
• t3_update_qset_coalesce(9)
• t3_sge_alloc_qset(9)
• t3_start_sge_timers(9)
• t3_stop_sge_timers(9)
• t3_free_sge_resources(9)
• t3_sge_start(9)
• t3_sge_stop_dma(9)
• t3_sge_stop(9)
• t3_sge_init(9)
• t3_sge_prep(9)

like I said — every. single. one. 💀 and yes, I typed them all, because that's the assignment and we don't do half-finished over here 🫶

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okurrr that's the whole page 💖 this icon came from ./drivers/net/ethernet/chelsio... (the full path in the SEE ALSO section is ./drivers/net/ethernet/chelsio/cxgb3/sge.c, iykyk), dated October 2026, and it's filed under calc_tx_descs(9). slay, go count those descriptors, bestie 🌈✨🎀