* rte_eth_stats_get seems slow
@ 2025-04-25 11:52 Morten Brørup
2025-04-26 15:23 ` Stephen Hemminger
0 siblings, 1 reply; 2+ messages in thread
From: Morten Brørup @ 2025-04-25 11:52 UTC (permalink / raw)
To: bruce.richardson; +Cc: Ian Stokes, dev
Bruce,
rte_eth_stats_get() on Intel NICs seems slow to me.
E.g. getting the stats on a single port takes ~132 us (~451,000 CPU cycles) using the igb driver, and ~50 us using the i40e driver.
Referring to the igb driver source code [1], it's 44 calls to E1000_READ_REG(), so the math says that each one takes 3 us (~10,000 CPU cycles).
Is this expected behavior?
It adds up, e.g. it takes a full millisecond to fetch the stats from eight ports using the igb driver.
[1]: https://elixir.bootlin.com/dpdk/v24.11.1/source/drivers/net/e1000/igb_ethdev.c#L1724
Med venlig hilsen / Kind regards,
-Morten Brørup
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: rte_eth_stats_get seems slow
2025-04-25 11:52 rte_eth_stats_get seems slow Morten Brørup
@ 2025-04-26 15:23 ` Stephen Hemminger
0 siblings, 0 replies; 2+ messages in thread
From: Stephen Hemminger @ 2025-04-26 15:23 UTC (permalink / raw)
To: Morten Brørup; +Cc: bruce.richardson, Ian Stokes, dev
On Fri, 25 Apr 2025 13:52:55 +0200
Morten Brørup <mb@smartsharesystems.com> wrote:
> Bruce,
>
> rte_eth_stats_get() on Intel NICs seems slow to me.
>
> E.g. getting the stats on a single port takes ~132 us (~451,000 CPU cycles) using the igb driver, and ~50 us using the i40e driver.
>
> Referring to the igb driver source code [1], it's 44 calls to E1000_READ_REG(), so the math says that each one takes 3 us (~10,000 CPU cycles).
>
> Is this expected behavior?
>
> It adds up, e.g. it takes a full millisecond to fetch the stats from eight ports using the igb driver.
>
> [1]: https://elixir.bootlin.com/dpdk/v24.11.1/source/drivers/net/e1000/igb_ethdev.c#L1724
>
>
> Med venlig hilsen / Kind regards,
> -Morten Brørup
>
Well reading each stat requires a PCI access. And PCI accesses are non-cached.
^ permalink raw reply [flat|nested] 2+ messages in thread
end of thread, other threads:[~2025-04-26 15:23 UTC | newest]
Thread overview: 2+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2025-04-25 11:52 rte_eth_stats_get seems slow Morten Brørup
2025-04-26 15:23 ` Stephen Hemminger
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).