linux-kernel - Re: [GIT PULL] x86 fixes for 2.6.30-rc8

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Message-ID: <alpine.LFD.2.01.0905251543570.3435@localhost.localdomain>
Date:	Mon, 25 May 2009 15:50:14 -0700 (PDT)
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	"H. Peter Anvin" <hpa@...or.com>
cc:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Ingo Molnar <mingo@...e.hu>,
	"Thomas Gleixner <tglx@...utronix.de> Suresh Siddha" 
	<suresh.siddha@...el.com>, Tejun Heo <tj@...nel.org>,
	Venkatesh Pallapadi <venkatesh.pallapadi@...el.com>,
	Zhang Rui <rui.zhang@...el.com>
Subject: Re: [GIT PULL] x86 fixes for 2.6.30-rc8



On Mon, 25 May 2009, H. Peter Anvin wrote:
>
> +static void wbinvd_local(void *unused)
> +{
> +	wbinvd();
> +}
> +
>  static void cpa_flush_array(unsigned long *start, int numpages, int cache,
>  			    int in_flags, struct page **pages)
>  {
> @@ -218,8 +223,9 @@ static void cpa_flush_array(unsigned long *start, int numpages, int cache,
>  
>  	/* 4M threshold */
>  	if (numpages >= 1024) {
> -		if (boot_cpu_data.x86_model >= 4)
> -			wbinvd();
> +		if (boot_cpu_data.x86 >= 4)
> +			on_each_cpu(wbinvd_local, NULL, 1);
> +

This looks a bit wrong.

Just above this, we've done

	on_each_cpu(__cpa_flush_range, NULL, 1);

and quite frankly, it seems to be that what we _should_ have done is to 
instead change that to

	long do_wbinvd = cache && numpages >= 1024;

	on_each_cpu(__cpa_flush_all, (void *)do_wbinvd, 1);
	if (!cache || do_wbinvd)
		return;

	.. do the cflush dance .. 

instead.

Now you made it do two different "on_each_cpu" things. Maybe it doesn't 
matter, but it just seems wrong.

		Linus
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