From: Dariusz Sosnowski <dsosnowski@nvidia.com>
To: Stephen Hemminger <stephen@networkplumber.org>
Cc: "NBU-Contact-Thomas Monjalon (EXTERNAL)" <thomas@monjalon.net>,
Ferruh Yigit <ferruh.yigit@amd.com>,
Andrew Rybchenko <andrew.rybchenko@oktetlabs.ru>,
Ori Kam <orika@nvidia.com>, "dev@dpdk.org" <dev@dpdk.org>
Subject: RE: [RFC] ethdev: fast path async flow API
Date: Mon, 29 Jan 2024 13:38:58 +0000 [thread overview]
Message-ID: <IA1PR12MB831101B86A42D7841B0DFB04A47E2@IA1PR12MB8311.namprd12.prod.outlook.com> (raw)
In-Reply-To: <IA1PR12MB83119E44D26E400D6CD50829A4742@IA1PR12MB8311.namprd12.prod.outlook.com>
Hi all,
> -----Original Message-----
> From: Dariusz Sosnowski <dsosnowski@nvidia.com>
> Sent: Tuesday, January 23, 2024 12:37
> To: Stephen Hemminger <stephen@networkplumber.org>
> Cc: NBU-Contact-Thomas Monjalon (EXTERNAL) <thomas@monjalon.net>;
> Ferruh Yigit <ferruh.yigit@amd.com>; Andrew Rybchenko
> <andrew.rybchenko@oktetlabs.ru>; Ori Kam <orika@nvidia.com>;
> dev@dpdk.org
> Subject: RE: [RFC] ethdev: fast path async flow API
>
> Hi Stephen,
>
> Sorry for such a late response.
>
> From: Stephen Hemminger <stephen@networkplumber.org>
> Sent: Thursday, January 4, 2024 02:08
> > On Wed, 3 Jan 2024 19:14:49 +0000
> > Dariusz Sosnowski <dsosnowski@nvidia.com> wrote:
> > > In summary, in my opinion extending the async flow API with bulking
> > capabilities or exposing the queue directly to the application is not desirable.
> > > This proposal aims to reduce the I-cache overhead in async flow API
> > > by
> > reusing the existing design pattern in DPDK - fast path functions are
> > inlined to the application code and they call cached PMD callbacks.
> >
> > Inline needs to more discouraged in DPDK, because it only works if
> > application ends up building with DPDK from source.
> > It doesn't work for the Linux distro packaging model and symbol
> > versioning, etc.
>
> I understand the problem. In that case, I have a proposal.
> I had a chat with Thomas regarding this RFC, and he noticed that there are 2
> separate changes proposed here:
>
> 1. Per-port callbacks for async flow API.
> - Moves specified callbacks to rte_flow_fp_ops struct and allow PMDs to
> register them dynamically.
> - Removes indirection at API level - no need to call rte_flow_ops_get().
> - Removes checking if callbacks are defined - either the default DPDK callback
> is used or the one provided by PMD.
> 2. Make async flow API functions inlineable.
>
> Change (1) won't break ABI (existing callbacks in rte_flow_ops can be marked
> as deprecated for now and phased out later) and in my opinion is less
> controversial compared to change (2).
>
> I'll rerun the benchmarks for both changes separately to compare their
> benefits in isolation.
> This would allow us to decide if change (2) is worth the drawbacks it
> introduces.
>
> What do you think?
I split the RFC into 2 parts:
1. Introduce per-port callbacks:
- Introduce rte_flow_fp_ops struct - holds callbacks for fast path calls, for each port. PMD registers callbacks through rte_flow_fp_ops_register().
- Relevant rte_flow_async_* functions just pass arguments to fast path callbacks. Validation checks are done only if RTE_FLOW_DEBUG macro is defined.
- Biggest difference is the removal of callback access through rte_flow_get_ops().
2. Inline async flow API functions.
- Relevant rte_flow_async_* functions definitions are moved to rte_flow.h and made inlineable.
Here are the results of the benchmark:
| | Avg Insertion | Diff over baseline | Avg Deletion | Diff over baseline |
|-----------------------|---------------|--------------------|--------------|--------------------|
| baseline (v24.03-rc0) | 5855.4 | | 9026.8 | |
| applied (1) | 6384.2 | +528.8 (+9%) | 10054.2 | +1027.4 (+11.4%) |
| applied (2) | 6434.6 | +579.2 (+9.9%) | 10011.4 | +984.6 (+10.9%) |
Results are in KFlows/sec.
The benchmark is continuously inserting and deleting 2M flow rules.
These rules match on IPv4 destination address and with a single action DROP.
Flow rules are inserted and deleted using a single flow queue.
Change (2) improves insertion rate performance by ~1% compared to (1), but decreases deletion rate by ~0.5%.
Based on these results, I think we can say that making rte_flow_async_*() calls inlineable may not be worth it compared to the issues it causes.
What do you all think about the results?
Best regards,
Dariusz Sosnowski
next prev parent reply other threads:[~2024-01-29 13:39 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-12-27 10:57 Dariusz Sosnowski
2023-12-27 17:39 ` Stephen Hemminger
2023-12-27 17:41 ` Stephen Hemminger
2023-12-28 13:53 ` Dariusz Sosnowski
2023-12-28 14:10 ` Ivan Malov
2024-01-03 18:01 ` Dariusz Sosnowski
2024-01-03 18:29 ` Ivan Malov
2024-01-04 13:13 ` Dariusz Sosnowski
2023-12-28 17:16 ` Stephen Hemminger
2024-01-03 19:14 ` Dariusz Sosnowski
2024-01-04 1:07 ` Stephen Hemminger
2024-01-23 11:37 ` Dariusz Sosnowski
2024-01-29 13:38 ` Dariusz Sosnowski [this message]
2024-01-29 17:36 ` Ferruh Yigit
2024-01-30 12:06 ` Dariusz Sosnowski
2024-01-30 12:17 ` Ferruh Yigit
2024-01-30 16:08 ` Dariusz Sosnowski
2024-01-04 8:47 ` Konstantin Ananyev
2024-01-04 16:08 ` Dariusz Sosnowski
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