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From: Jakub Kicinski <kuba@kernel.org>
To: Ahmed Zaki <ahmed.zaki@intel.com>
Cc: mkubecek@suse.cz, andrew@lunn.ch,
	Willem de Bruijn <willemdebruijn.kernel@gmail.com>,
	Wojciech Drewek <wojciech.drewek@intel.com>,
	corbet@lwn.net, netdev@vger.kernel.org,
	linux-doc@vger.kernel.org, jesse.brandeburg@intel.com,
	edumazet@google.com, anthony.l.nguyen@intel.com,
	horms@kernel.org, vladimir.oltean@nxp.com,
	intel-wired-lan@lists.osuosl.org, pabeni@redhat.com,
	davem@davemloft.net
Subject: Re: [Intel-wired-lan] [PATCH net-next v2 1/6] net: ethtool: allow symmetric RSS hash for any flow type
Date: Fri, 6 Oct 2023 17:22:48 -0700	[thread overview]
Message-ID: <20231006172248.15c2e415@kernel.org> (raw)
In-Reply-To: <20231006224726.443836-2-ahmed.zaki@intel.com>

On Fri,  6 Oct 2023 16:47:21 -0600 Ahmed Zaki wrote:
> Symmetric RSS hash functions are beneficial in applications that monitor
> both Tx and Rx packets of the same flow (IDS, software firewalls, ..etc).
> Getting all traffic of the same flow on the same RX queue results in
> higher CPU cache efficiency.
> 
> Only fields that has counterparts in the other direction can be
> accepted; IP src/dst and L4 src/dst ports.
> 
> The user may request RSS hash symmetry for a specific flow type, via:
> 
>     # ethtool -N|-U eth0 rx-flow-hash <flow_type> s|d|f|n symmetric
> 
> or turn symmetry off (asymmetric) by:
> 
>     # ethtool -N|-U eth0 rx-flow-hash <flow_type> s|d|f|n

Thanks for the changes, code looks good!

The question left unanswered is whether we should care about the exact
implementation of the symmetry (xor, xor duplicate, sort fields).
Toeplitz-based RSS is very precisely specified, so we may want to carry
that precision into the symmetric behavior. I have a weak preference 
to do so... but no willingness to argue with you, so let me put Willem
on the spot and have him make a decision :)

Please make sure to CC Willem and anyone else who commented on previous
revisions on future versions!
_______________________________________________
Intel-wired-lan mailing list
Intel-wired-lan@osuosl.org
https://lists.osuosl.org/mailman/listinfo/intel-wired-lan

WARNING: multiple messages have this Message-ID (diff)
From: Jakub Kicinski <kuba@kernel.org>
To: Ahmed Zaki <ahmed.zaki@intel.com>
Cc: netdev@vger.kernel.org, intel-wired-lan@lists.osuosl.org,
	linux-doc@vger.kernel.org, corbet@lwn.net,
	jesse.brandeburg@intel.com, anthony.l.nguyen@intel.com,
	davem@davemloft.net, edumazet@google.com, pabeni@redhat.com,
	vladimir.oltean@nxp.com, andrew@lunn.ch, horms@kernel.org,
	mkubecek@suse.cz, Wojciech Drewek <wojciech.drewek@intel.com>,
	Willem de Bruijn <willemdebruijn.kernel@gmail.com>
Subject: Re: [PATCH net-next v2 1/6] net: ethtool: allow symmetric RSS hash for any flow type
Date: Fri, 6 Oct 2023 17:22:48 -0700	[thread overview]
Message-ID: <20231006172248.15c2e415@kernel.org> (raw)
In-Reply-To: <20231006224726.443836-2-ahmed.zaki@intel.com>

On Fri,  6 Oct 2023 16:47:21 -0600 Ahmed Zaki wrote:
> Symmetric RSS hash functions are beneficial in applications that monitor
> both Tx and Rx packets of the same flow (IDS, software firewalls, ..etc).
> Getting all traffic of the same flow on the same RX queue results in
> higher CPU cache efficiency.
> 
> Only fields that has counterparts in the other direction can be
> accepted; IP src/dst and L4 src/dst ports.
> 
> The user may request RSS hash symmetry for a specific flow type, via:
> 
>     # ethtool -N|-U eth0 rx-flow-hash <flow_type> s|d|f|n symmetric
> 
> or turn symmetry off (asymmetric) by:
> 
>     # ethtool -N|-U eth0 rx-flow-hash <flow_type> s|d|f|n

Thanks for the changes, code looks good!

The question left unanswered is whether we should care about the exact
implementation of the symmetry (xor, xor duplicate, sort fields).
Toeplitz-based RSS is very precisely specified, so we may want to carry
that precision into the symmetric behavior. I have a weak preference 
to do so... but no willingness to argue with you, so let me put Willem
on the spot and have him make a decision :)

Please make sure to CC Willem and anyone else who commented on previous
revisions on future versions!

  reply	other threads:[~2023-10-07  0:22 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-10-06 22:47 [Intel-wired-lan] [PATCH net-next v2 0/6] Support symmetric RSS (Toeplitz) hash Ahmed Zaki
2023-10-06 22:47 ` Ahmed Zaki
2023-10-06 22:47 ` [Intel-wired-lan] [PATCH net-next v2 1/6] net: ethtool: allow symmetric RSS hash for any flow type Ahmed Zaki
2023-10-06 22:47   ` Ahmed Zaki
2023-10-07  0:22   ` Jakub Kicinski [this message]
2023-10-07  0:22     ` Jakub Kicinski
2023-10-07  9:01     ` [Intel-wired-lan] " Willem de Bruijn
2023-10-07  9:01       ` Willem de Bruijn
2023-10-10 20:10       ` [Intel-wired-lan] " Ahmed Zaki
2023-10-10 20:10         ` Ahmed Zaki
2023-10-06 22:47 ` [Intel-wired-lan] [PATCH net-next v2 2/6] ice: fix ICE_AQ_VSI_Q_OPT_RSS_* register values Ahmed Zaki
2023-10-06 22:47   ` Ahmed Zaki
2023-10-09 16:37   ` [Intel-wired-lan] " Jakub Kicinski
2023-10-09 16:37     ` Jakub Kicinski
2023-10-10 20:08     ` [Intel-wired-lan] " Ahmed Zaki
2023-10-10 20:08       ` Ahmed Zaki
2023-10-06 22:47 ` [Intel-wired-lan] [PATCH net-next v2 3/6] ice: refactor RSS configuration Ahmed Zaki
2023-10-06 22:47   ` Ahmed Zaki
2023-10-06 22:47 ` [Intel-wired-lan] [PATCH net-next v2 4/6] ice: refactor the FD and RSS flow ID generation Ahmed Zaki
2023-10-06 22:47   ` Ahmed Zaki
2023-10-06 22:47 ` [Intel-wired-lan] [PATCH net-next v2 5/6] ice: enable symmetric RSS Toeplitz hash for any flow type Ahmed Zaki
2023-10-06 22:47   ` Ahmed Zaki
2023-10-06 22:47 ` [Intel-wired-lan] [PATCH net-next v2 6/6] iavf: enable symmetric RSS Toeplitz hash Ahmed Zaki
2023-10-06 22:47   ` Ahmed Zaki

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