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

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Message-ID: <20240725153519.GA21016@linuxonhyperv3.guj3yctzbm1etfxqx2vob5hsef.xx.internal.cloudapp.net>
Date: Thu, 25 Jul 2024 08:35:19 -0700
From: Saurabh Singh Sengar <ssengar@...ux.microsoft.com>
To: Nuno Das Neves <nunodasneves@...ux.microsoft.com>
Cc: kys@...rosoft.com, haiyangz@...rosoft.com, wei.liu@...nel.org,
	decui@...rosoft.com, linux-hyperv@...r.kernel.org,
	linux-kernel@...r.kernel.org, ssengar@...rosoft.com,
	srivatsa@...il.mit.edu
Subject: Re: [PATCH] Drivers: hv: vmbus: Deferring per cpu tasks

On Thu, Jul 25, 2024 at 08:23:21AM -0700, Nuno Das Neves wrote:
> 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()?

Thanks, will send v2 correcting this.

- Saurabh

> 
> > 
> > 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>