From: Stephen Hemminger <stephen@networkplumber.org>
To: "Lombardo, Ed" <Ed.Lombardo@netscout.com>
Cc: Ivan Malov <ivan.malov@arknetworks.am>, users <users@dpdk.org>
Subject: Re: dpdk Tx falling short
Date: Sat, 5 Jul 2025 12:08:34 -0700 [thread overview]
Message-ID: <20250705120834.78849e56@hermes.local> (raw)
In-Reply-To: <CH3PR01MB84705581A7FED5E8F78C5F738F4DA@CH3PR01MB8470.prod.exchangelabs.com>
On Sat, 5 Jul 2025 17:36:08 +0000
"Lombardo, Ed" <Ed.Lombardo@netscout.com> wrote:
> Hi Stephen,
> I saw your response to more mempools and cache behavior.
>
> I have a goal to support 2x100G next, and if I can't get 10G with DPDK then something is seriously wrong.
>
> Should I build the dpdk static libraries with LTO?
>
> Thanks,
> Ed
Are you doing anything in the fast path that is an obvious cache miss.
at 10Gbit/sec and size of 84 bytes = 67.2ns
CPU's haven't got that much faster 3G cpu that is 201 cycles.
Single cache miss is 32ns, so two cache misses means per-packet budget is gone.
Obvious cache misses.
- passing packets to worker with ring
- using spinlocks (cost 16ns)
- fetching TSC
- syscalls?
Also, never ever use floating point.
Kernel related and older but worth looking at:
https://people.netfilter.org/hawk/presentations/LCA2015/net_stack_challenges_100G_LCA2015.pdf
next prev parent reply other threads:[~2025-07-05 19:08 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-07-03 20:14 Lombardo, Ed
2025-07-03 21:49 ` Stephen Hemminger
2025-07-04 5:58 ` Rajesh Kumar
2025-07-04 11:44 ` Ivan Malov
2025-07-04 14:49 ` Stephen Hemminger
2025-07-05 17:36 ` Lombardo, Ed
2025-07-05 19:02 ` Stephen Hemminger
2025-07-05 19:08 ` Stephen Hemminger [this message]
2025-07-06 0:03 ` Lombardo, Ed
2025-07-06 16:02 ` Stephen Hemminger
2025-07-06 17:44 ` Lombardo, Ed
2025-07-05 17:33 ` Lombardo, Ed
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