linux-kernel - RE: [PATCH v2] net: netvsc: Update default VMBus channels

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Message-ID:
 <CH2PPF910B3338D6A9D957F4BB241ED695ACA872@CH2PPF910B3338D.namprd21.prod.outlook.com>
Date: Wed, 14 Aug 2024 18:23:56 +0000
From: Haiyang Zhang <haiyangz@...rosoft.com>
To: Erni Sri Satya Vennela <ernis@...ux.microsoft.com>, KY Srinivasan
	<kys@...rosoft.com>, "wei.liu@...nel.org" <wei.liu@...nel.org>, Dexuan Cui
	<decui@...rosoft.com>, "davem@...emloft.net" <davem@...emloft.net>,
	"edumazet@...gle.com" <edumazet@...gle.com>, "kuba@...nel.org"
	<kuba@...nel.org>, "pabeni@...hat.com" <pabeni@...hat.com>,
	"linux-hyperv@...r.kernel.org" <linux-hyperv@...r.kernel.org>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC: Erni Sri Satya Vennela <ernis@...rosoft.com>
Subject: RE: [PATCH v2] net: netvsc: Update default VMBus channels



> -----Original Message-----
> From: Erni Sri Satya Vennela <ernis@...ux.microsoft.com>
> Sent: Wednesday, August 14, 2024 12:59 PM
> To: KY Srinivasan <kys@...rosoft.com>; Haiyang Zhang
> <haiyangz@...rosoft.com>; wei.liu@...nel.org; Dexuan Cui
> <decui@...rosoft.com>; davem@...emloft.net; edumazet@...gle.com;
> kuba@...nel.org; pabeni@...hat.com; linux-hyperv@...r.kernel.org;
> netdev@...r.kernel.org; linux-kernel@...r.kernel.org
> Cc: Erni Sri Satya Vennela <ernis@...rosoft.com>; Erni Sri Satya Vennela
> <ernis@...ux.microsoft.com>
> Subject: [PATCH v2] net: netvsc: Update default VMBus channels
> 
> Change VMBus channels macro (VRSS_CHANNEL_DEFAULT) in
> Linux netvsc from 8 to 16 to align with Azure Windows VM
> and improve networking throughput.
> 
> For VMs having less than 16 vCPUS, the channels depend
> on number of vCPUs. Between 16 to 32 vCPUs, the channels
> default to VRSS_CHANNEL_DEFAULT. For greater than 32 vCPUs,
> set the channels to number of physical cores / 2 as a way
> to optimize CPU resource utilization and scale for high-end
> processors with many cores.
> Maximum number of channels are by default set to 64.
> 
> Based on this change the subchannel creation would change as follows:
> 
> -------------------------------------------------------------
> |No. of vCPU	|dev_info->num_chn	|subchannel created |
> -------------------------------------------------------------
> |  0-16		|	16		|	vCPU	    |
> | >16 & <=32	|	16		|	16          |
> | >32 & <=128	|	vCPU/2		|	vCPU/2      |
> | >128		|	vCPU/2		|	64          |
> -------------------------------------------------------------
> 
> Performance tests showed significant improvement in throughput:
> - 0.54% for 16 vCPUs
> - 0.83% for 32 vCPUs
> - 1.76% for 48 vCPUs
> - 10.35% for 64 vCPUs
> - 13.47% for 96 vCPUs
> 
> Signed-off-by: Erni Sri Satya Vennela <ernis@...ux.microsoft.com>

Reviewed-by: Haiyang Zhang <haiyangz@...rosoft.com>
Thanks.