linux-kernel - Re: [PATCH] Drivers: hv: vmbus: Deferring per cpu tasks

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Message-ID: <133be5cb-761e-4646-96ec-b6b53f0c1097@linux.microsoft.com>
Date: Thu, 25 Jul 2024 08:23:21 -0700
From: Nuno Das Neves <nunodasneves@...ux.microsoft.com>
To: Saurabh Sengar <ssengar@...ux.microsoft.com>, kys@...rosoft.com,
 haiyangz@...rosoft.com, wei.liu@...nel.org, decui@...rosoft.com,
 linux-hyperv@...r.kernel.org, linux-kernel@...r.kernel.org
Cc: ssengar@...rosoft.com, srivatsa@...il.mit.edu
Subject: Re: [PATCH] Drivers: hv: vmbus: Deferring per cpu tasks

On 7/24/2024 10:26 PM, Saurabh Sengar wrote:
> Currently on a very large system with 1780 CPUs, hv_acpi_init takes
> around 3 seconds to complete for all the CPUs. This is because of
> sequential synic initialization for each CPU.
> 
> Defer these tasks so that each CPU executes hv_acpi_init in parallel
> to take full advantage of multiple CPUs.

I think you mean hv_synic_init() here, not hv_acpi_init()?

> 
> This solution saves around 2 seconds of boot time on a 1780 CPU system,
> that around 66% improvement in the existing logic.
> 
> Signed-off-by: Saurabh Sengar <ssengar@...ux.microsoft.com>
> ---
>  drivers/hv/vmbus_drv.c | 33 ++++++++++++++++++++++++++++++---
>  1 file changed, 30 insertions(+), 3 deletions(-)
> 

LGTM otherwise.

Reviewed-by: Nuno Das Neves <nunodasneves@...ux.microsoft.com>