linux-kernel - Re: [PATCH 4/4] x86: Minimize SRAT messages

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Message-ID: <20110227120348.GE16453@elte.hu>
Date:	Sun, 27 Feb 2011 13:03:48 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	Mike Travis <travis@....com>
Cc:	David Rientjes <rientjes@...gle.com>,
	Jack Steiner <steiner@....com>, Robin Holt <holt@....com>,
	Len Brown <len.brown@...el.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Yinghai Lu <yhlu.kernel@...il.com>, linux-acpi@...r.kernel.org,
	x86@...nel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 4/4] x86: Minimize SRAT messages


* Mike Travis <travis@....com> wrote:

> Condense the SRAT: messages to show all the APIC id's on one line for
> each Node.  This not only saves space in the log buf, it also makes
> it easier to spot inconsistencies in core to node placement.
> 
> On a system with 2368 cores on 248 nodes the change will be...
> 
> Was 2368 lines (for 2368 cores):
> 
>  779 [0] SRAT: PXM 0 -> APIC 0x0000 -> Node 0
>  780 [0] SRAT: PXM 0 -> APIC 0x0002 -> Node 0
>  781 [0] SRAT: PXM 0 -> APIC 0x0004 -> Node 0
>  ...
>  3145 [0] SRAT: PXM 247 -> APIC 0x3df0 -> Node 247
>  3146 [0] SRAT: PXM 247 -> APIC 0x3df2 -> Node 247
> 
> Now it's 248 lines (for 248 Nodes):
> 
>  821 [0] SRAT: Node 0: PXM:APIC 0:0x0 :0x2 :0x4 :0x10 :0x12 ...
>  822 [0] SRAT: Node 1: PXM:APIC 1:0x40 :0x42 :0x44 :0x50 :0x52 ...
>  823 [0] SRAT: Node 2: PXM:APIC 2:0x80 :0x82 :0x84 :0x90 :0x92 ...
>  ...
>  1067 [0] SRAT: Node 246: PXM:APIC 246:0x3d80 :0x3d82 :0x3d84 :0x3d90 ...
>  1068 [0] SRAT: Node 247: PXM:APIC 247:0x3dc0 :0x3dc2 :0x3dc4 :0x3dd2 ...
> 
> Signed-off-by: Mike Travis <travis@....com>
> Reviewed-by: Jack Steiner <steiner@....com>
> Reviewed-by: Robin Holt <holt@....com>
> ---
>  arch/x86/mm/srat_64.c |   19 +++++++++++++++++--
>  drivers/acpi/numa.c   |    7 +++++++
>  2 files changed, 24 insertions(+), 2 deletions(-)
> 
> --- linux.orig/arch/x86/mm/srat_64.c
> +++ linux/arch/x86/mm/srat_64.c
> @@ -110,6 +110,12 @@ void __init acpi_numa_slit_init(struct a
>  	memblock_x86_reserve_range(phys, phys + length, "ACPI SLIT");
>  }
>  
> +/*
> + * Keep track of previous node and PXM values so we can combine
> + * same ones onto a single line.
> + */
> +static int __initdata last_node = NUMA_NO_NODE, last_pxm =  PXM_INVAL;
> +
>  /* Callback for Proximity Domain -> x2APIC mapping */
>  void __init
>  acpi_numa_x2apic_affinity_init(struct acpi_srat_x2apic_cpu_affinity *pa)
> @@ -141,8 +147,17 @@ acpi_numa_x2apic_affinity_init(struct ac
>  	set_apicid_to_node(apic_id, node);
>  	node_set(node, cpu_nodes_parsed);
>  	acpi_numa = 1;
> -	printk(KERN_INFO "SRAT: PXM %u -> APIC 0x%04x -> Node %u\n",
> -	       pxm, apic_id, node);
> +	if (node != last_node) {
> +		pr_info("SRAT: Node %u: PXM:APIC %u:0x%x",
> +		       node, pxm, apic_id);
> +		last_node = node;
> +		last_pxm = pxm;
> +	} else if (pxm != last_pxm) {
> +		pr_cont(" %u:0x%x", pxm, apic_id);
> +		last_pxm = pxm;
> +	} else {
> +		pr_cont(" :0x%x", apic_id);
> +	}
>  }
>  
>  /* Callback for Proximity Domain -> LAPIC mapping */
> --- linux.orig/drivers/acpi/numa.c
> +++ linux/drivers/acpi/numa.c
> @@ -286,6 +286,13 @@ int __init acpi_numa_init(void)
>  	if (!acpi_table_parse(ACPI_SIG_SRAT, acpi_parse_srat)) {
>  		acpi_table_parse_srat(ACPI_SRAT_TYPE_X2APIC_CPU_AFFINITY,
>  				     acpi_parse_x2apic_affinity, 0);
> +		/*
> +		 * Parsing ACPI_SRAT_TYPE_X2APIC_CPU_AFFINITY entries place
> +		 * multiple CPU's on the same Node line.  This can leave the
> +		 * last entry "dangling" without a newline.  Insert it here.
> +		 */
> +		pr_cont("\n");

This is quite ugly as it breaks the genericity of the ACPI parsing here. Is there no 
cleaner method that keeps this deinit \n printing somehow within the realm of x86?

Also, can there be cases where there's no 'dangling' line pending? In that case the 
\n will be superfluous here.

Thanks,

	Ingo
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