From: Scotty Bauer <sbauer@eng.utah.edu>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: tglx@linutronix.de, mingo@redhat.com,
linux-kernel@vger.kernel.org, x86@kernel.org,
Borislav Petkov <bp@alien8.de>
Subject: Re: [PATCH] x86/smpboot: check if CLFLUSH is actually necessary
Date: Wed, 11 Feb 2015 16:10:12 -0700 [thread overview]
Message-ID: <54DBE154.5040204@eng.utah.edu> (raw)
In-Reply-To: <54DBCFD6.8000509@zytor.com>
On 02/11/2015 02:55 PM, H. Peter Anvin wrote:
> On 01/30/2015 01:26 PM, Scotty Bauer wrote:
>> mwait_play_dead previously issued a CLFLUSH to work around a bug on
>> some xeon processors. We can now determine if the CPU is a buggy CPU.
>> This patch checks if if we're on a buggy CPU which allows non-buggy
>> cpu's to eliminate the CLFLUSH.
> Here is my first question: does this matter at all? Otherwise I don't
> see a point.
>
> -hpa
>
>
Do you get the same effect? Sure, but is the previous way the right way to do it? In my opinion no, but I'm not the one merging code its up to someone more experienced to determine if the change is warranted. The change is slightly faster on non-buggy cpu, but like you mention, is that relevant when the machine is going into idle?
next prev parent reply other threads:[~2015-02-11 23:10 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-01-30 21:26 [PATCH] x86/smpboot: check if CLFLUSH is actually necessary Scotty Bauer
2015-01-30 23:31 ` Borislav Petkov
2015-02-06 16:05 ` Borislav Petkov
2015-02-06 16:13 ` [PATCH] x86, smpboot: Call CLFLUSH only on X86_BUG_CLFLUSH_MONITOR-affected CPUs Borislav Petkov
2015-02-11 18:39 ` Scotty Bauer
2015-02-11 20:25 ` Borislav Petkov
2015-02-11 21:55 ` [PATCH] x86/smpboot: check if CLFLUSH is actually necessary H. Peter Anvin
2015-02-11 21:55 ` H. Peter Anvin
2015-02-11 23:10 ` Scotty Bauer [this message]
2015-02-12 9:16 ` Borislav Petkov
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