linux-kernel - Re: [PATCH 4/8] SGI x86_64 UV: Limit the number of ACPI messages

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Date:	Fri, 23 Oct 2009 21:29:47 -0600
From:	Bjorn Helgaas <bjorn.helgaas@...com>
To:	Mike Travis <travis@....com>
Cc:	Ingo Molnar <mingo@...e.hu>, Thomas Gleixner <tglx@...utronix.de>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Jack Steiner <steiner@....com>,
	Zhang Rui <rui.zhang@...el.com>, Len Brown <lenb@...nel.org>,
	Thomas Renninger <trenn@...e.de>,
	Alexey Dobriyan <adobriyan@...il.com>,
	Myron Stowe <myron.stowe@...com>,
	Feng Tang <feng.tang@...el.com>,
	Suresh Siddha <suresh.b.siddha@...el.com>,
	Yinghai Lu <yhlu.kernel@...il.com>, linux-acpi@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 4/8] SGI x86_64 UV: Limit the number of ACPI messages

On Fri, 2009-10-23 at 18:37 -0500, Mike Travis wrote:
> plain text document attachment (limit_acpi)
> Limit number of ACPI messages of the form:
> 
> [    0.000000] ACPI: LSAPIC (acpi_id[0x00] lsapic_id[0x00] lsapic_eid[0x00] enabled)
> 
> [   99.638655] processor ACPI0007:00: registered as cooling_device0
> 
> Cc: Zhang Rui <rui.zhang@...el.com>
> Cc: Len Brown <lenb@...nel.org>
> Cc: Thomas Renninger <trenn@...e.de>
> Cc: Bjorn Helgaas <bjorn.helgaas@...com>
> Cc: Alexey Dobriyan <adobriyan@...il.com>
> Cc: Myron Stowe <myron.stowe@...com>
> Cc: Feng Tang <feng.tang@...el.com>
> Cc: Suresh Siddha <suresh.b.siddha@...el.com>
> Cc: Yinghai Lu <yhlu.kernel@...il.com>
> Cc: linux-acpi@...r.kernel.org
> Cc: linux-kernel@...r.kernel.org
> Signed-off-by: Mike Travis <travis@....com>
> ---
>  drivers/acpi/fan.c            |    7 ++++++-
>  drivers/acpi/processor_core.c |    8 ++++++--
>  drivers/acpi/tables.c         |   15 ++++++++++-----
>  3 files changed, 22 insertions(+), 8 deletions(-)
> 
> --- linux.orig/drivers/acpi/fan.c
> +++ linux/drivers/acpi/fan.c
> @@ -243,6 +243,7 @@
>  	int result = 0;
>  	int state = 0;
>  	struct thermal_cooling_device *cdev;
> +	static int msgcnt;
>  
>  	if (!device)
>  		return -EINVAL;
> @@ -267,7 +268,11 @@
>  		goto end;
>  	}
>  
> -	dev_info(&device->dev, "registered as cooling_device%d\n", cdev->id);
> +	if (msgcnt < 4 || !limit_console_output(false)) {
> +		dev_info(&device->dev,
> +			"registered as cooling_device%d\n", cdev->id);
> +		msgcnt++;
> +	}

I'm personally not in favor of printing some, but not all, of these
messages.  That leads to questions when analyzing a dmesg log, such as
"Hmm, I see I have 64 CPUs, but only 0-3 are registered as cooling
devices.  Does that mean something is wrong?"

But I would be glad to see this particular message removed completely.

>  	device->driver_data = cdev;
>  	result = sysfs_create_link(&device->dev.kobj,
> --- linux.orig/drivers/acpi/processor_core.c
> +++ linux/drivers/acpi/processor_core.c
> @@ -775,6 +775,7 @@
>  	struct acpi_processor *pr = NULL;
>  	int result = 0;
>  	struct sys_device *sysdev;
> +	static int msgcnt;
>  
>  	pr = kzalloc(sizeof(struct acpi_processor), GFP_KERNEL);
>  	if (!pr)
> @@ -845,8 +846,11 @@
>  		goto err_power_exit;
>  	}
>  
> -	dev_info(&device->dev, "registered as cooling_device%d\n",
> -		 pr->cdev->id);
> +	if (msgcnt < 4 || !limit_console_output(false)) {
> +		dev_info(&device->dev, "registered as cooling_device%d\n",
> +			 pr->cdev->id);
> +		msgcnt++;
> +	}
>  
>  	result = sysfs_create_link(&device->dev.kobj,
>  				   &pr->cdev->device.kobj,
> --- linux.orig/drivers/acpi/tables.c
> +++ linux/drivers/acpi/tables.c
> @@ -170,11 +170,16 @@
>  	case ACPI_MADT_TYPE_LOCAL_SAPIC:
>  		{
>  			struct acpi_madt_local_sapic *p =
> -			    (struct acpi_madt_local_sapic *)header;
> -			printk(KERN_INFO PREFIX
> -			       "LSAPIC (acpi_id[0x%02x] lsapic_id[0x%02x] lsapic_eid[0x%02x] %s)\n",
> -			       p->processor_id, p->id, p->eid,
> -			       (p->lapic_flags & ACPI_MADT_ENABLED) ? "enabled" : "disabled");
> +				(struct acpi_madt_local_sapic *)header;
> +
> +			if (p->eid < 8 || !limit_console_output(false))
> +				printk(KERN_INFO PREFIX
> +					"LSAPIC (acpi_id[0x%02x] "
> +						"lsapic_id[0x%02x] "
> +						"lsapic_eid[0x%02x] %s)\n",
> +					p->processor_id, p->id, p->eid,
> +					(p->lapic_flags & ACPI_MADT_ENABLED) ?
> +						"enabled" : "disabled");

I know we print way too much stuff for every processor, but again, I'd
rather see all CPUs or none.  I think there's a little more value in
this one than the cooling device one (probably because I do a lot of
platform bringup), but it could certainly be made KERN_DEBUG and/or
combined with another processor discovery line.

Bjorn

>  		}
>  		break;
>  
> 

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