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From: Stephen Hemminger <stephen@networkplumber.org>
To: fwefew 4t4tg <7532yahoo@gmail.com>
Cc: users@dpdk.org
Subject: Re: need definitions / references
Date: Thu, 17 Mar 2022 09:48:24 -0700
Message-ID: <20220317094824.423d2a83@hermes.local> (raw)
In-Reply-To: <CA+Tq66WzmeD3DeTKVCvh0ZB4-dmkU_ym=uT_AL35Jy6z0PawZQ@mail.gmail.com>

On Thu, 17 Mar 2022 12:05:33 -0400
fwefew 4t4tg <7532yahoo@gmail.com> wrote:

> DPDK provides but does not define (that I can see at least) these TXQ
> config fields. What are these fields what do they do?
> https://doc.dpdk.org/api/structrte__eth__thresh.html
> uint8_t pthresh
> uint8_t hthresh
> uint8_t wthresh

These are low level details inherited from original Intel NIC's (ie ixgbe)
they only apply to some NICs. They are used to control the ring threshold
values relating to PCI.

In rte_ethdev.h
 * A structure used to configure the ring threshold registers of an Rx/Tx
 * queue for an Ethernet port.
struct rte_eth_thresh {
	uint8_t pthresh; /**< Ring prefetch threshold. */
	uint8_t hthresh; /**< Ring host threshold. */
	uint8_t wthresh; /**< Ring writeback threshold. */

> And here: What is the RS bit?
> https://doc.dpdk.org/api/structrte__eth__txconf.html
> uint16_t tx_rs_thresh.

Ready to Send?

> And some what unrelated: What is a ``doorbell"? this is something I
> continue to run into esp. in Mellanox NIC papers? Doorbell counts are
> reported for AWS NICs at least with xstats api:
> tx_q0_doorbells: 18812
> tx_q1_doorbells: 18861

These are how many times driver needed to poke hardware to tell it
that new packets are ready to send.

  reply	other threads:[~2022-03-17 16:48 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-03-17 16:05 fwefew 4t4tg
2022-03-17 16:48 ` Stephen Hemminger [this message]
2022-03-17 16:59   ` fwefew 4t4tg

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