linux-kernel - Re: [PATCH 1/7] x86: Limit the number of processor bootup messages

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Message-ID: <20091112180910.GA8598@elte.hu>
Date:	Thu, 12 Nov 2009 19:09:10 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	Mike Travis <travis@....com>
Cc:	Thomas Gleixner <tglx@...utronix.de>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Heiko Carstens <heiko.carstens@...ibm.com>,
	Roland Dreier <rdreier@...co.com>,
	Randy Dunlap <rdunlap@...otime.net>, Tejun Heo <tj@...nel.org>,
	Andi Kleen <andi@...stfloor.org>,
	Greg Kroah-Hartman <gregkh@...e.de>,
	Yinghai Lu <yhlu.kernel@...il.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	David Rientjes <rientjes@...gle.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Rusty Russell <rusty@...tcorp.com.au>,
	Hidetoshi Seto <seto.hidetoshi@...fujitsu.com>,
	Jack Steiner <steiner@....com>,
	Frederic Weisbecker <fweisbec@...il.com>, x86@...nel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/7] x86: Limit the number of processor bootup messages


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

> --- linux.orig/arch/x86/kernel/smpboot.c
> +++ linux/arch/x86/kernel/smpboot.c
> @@ -442,6 +442,84 @@
>  		return c->llc_shared_map;
>  }
>  
> +/* Summarize Processor Information */
> +static void __init summarize_cpu_info(void)
> +{
> +	cpumask_var_t cpulist, cpusdone;
> +	int cpu;
> +	int err = 0;
> +
> +	if (!alloc_cpumask_var(&cpulist, GFP_KERNEL))
> +		err = 1;
> +	else if (!alloc_cpumask_var(&cpusdone, GFP_KERNEL)) {
> +		free_cpumask_var(cpulist);
> +		err = 1;
> +	}
> +	if (err) {
> +		printk(KERN_INFO "Can't print processor summaries\n");
> +		return;
> +	}
> +
> +	cpumask_clear(cpusdone);
> +	for (cpu = 0; cpu < nr_cpu_ids; cpu++) {
> +		struct cpuinfo_x86 *c;
> +		char buf[128];
> +		int ncpu, len;
> +		unsigned long minlpj, maxlpj, avglpj = 0;
> +
> +		/* skip if cpu has already been displayed */
> +		if (cpumask_test_cpu(cpu, cpusdone))
> +			continue;
> +
> +		c = &cpu_data(cpu);
> +		minlpj = ULONG_MAX;
> +		maxlpj = 0;
> +
> +		cpumask_clear(cpulist);
> +
> +		/* collate all cpus with same specifics */
> +		for (ncpu = cpu; ncpu < nr_cpu_ids; ncpu++) {
> +			struct cpuinfo_x86 *n = &cpu_data(ncpu);
> +
> +			if (c->x86 != n->x86 ||
> +			    c->x86_vendor != n->x86_vendor ||
> +			    c->x86_model  != n->x86_model  ||
> +			    c->x86_mask   != n->x86_mask   ||
> +			    strcmp(c->x86_model_id, n->x86_model_id))
> +				continue;
> +
> +			cpumask_set_cpu(ncpu, cpulist);
> +			cpumask_set_cpu(ncpu, cpusdone);
> +
> +			if (cpu_data(ncpu).loops_per_jiffy < minlpj)
> +				minlpj = cpu_data(ncpu).loops_per_jiffy;
> +
> +			if (cpu_data(ncpu).loops_per_jiffy > maxlpj)
> +				maxlpj = cpu_data(ncpu).loops_per_jiffy;
> +
> +			avglpj += cpu_data(ncpu).loops_per_jiffy;
> +		}
> +
> +		len = cpulist_scnprintf(buf, sizeof(buf), cpulist);
> +		printk(KERN_INFO
> +			"Processor Information for CPUS: %s%s\n",
> +				buf, (len == sizeof(buf)-1) ? "..." : "");
> +
> +		printk(KERN_INFO);
> +		print_cpu_info(c);
> +
> +		avglpj /= cpumask_weight(cpulist);
> +		printk(KERN_INFO "BogoMIPS: MIN %lu.%02lu (%lu) "
> +			"AVG %lu.%02lu (%lu) MAX %lu.%02lu (%lu)\n",
> +			minlpj/(500000/HZ), (minlpj/(5000/HZ)) % 100, minlpj,
> +			avglpj/(500000/HZ), (avglpj/(5000/HZ)) % 100, avglpj,
> +			maxlpj/(500000/HZ), (maxlpj/(5000/HZ)) % 100, maxlpj);
> +	}
> +
> +	free_cpumask_var(cpusdone);
> +	free_cpumask_var(cpulist);
> +}
> +

Sigh, that's _way_ too complex.

If you cannot print it in a summarized way without carrying over stupid 
state like bitmaps then please do the simple and obvious, and print:

booting CPUs: #0 #1 #2 #3 #4 #5 #6 ...

It's a really long line with 4096 CPUs but that's not a big problem - on 
most systems it will look sane.

	Ingo
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