From: Andi Kleen <andi@firstfloor.org>
To: Thomas Hellstrom <thellstrom@vmware.com>
Cc: Andi Kleen <andi@firstfloor.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"mingo@elte.hu" <mingo@elte.hu>,
"venkatesh.pallipadi@intel.com" <venkatesh.pallipadi@intel.com>
Subject: Re: [PATCH] x86: Use clflush() instead of wbinvd() whenever possible when changing mapping
Date: Fri, 24 Jul 2009 15:16:49 +0200 [thread overview]
Message-ID: <20090724131649.GC2045@basil.fritz.box> (raw)
In-Reply-To: <4A699784.9020803@vmware.com>
> No. It was motivated by the assumption that wbinvd() is just bad:
Ok, got it now.
> Qoute:
>
> WBINVD is a very nasty operation. I was talking to some CPU people and they
> really recommended to get rid of it as far as possible. Stopping the CPU
> for msecs is just wrong and there are apparently even some theoretical live
> lock situations. - It is not interruptible in earlier VT versions and
> messes up real time in the hypervisor. Some people were doing KVM on rt
> kernels and had latency spikes from that.
>
>
> /Qoute
> (I believe you wrote that ?)
Yes. That's still true and that's one reason to not use it.
-Andi
next prev parent reply other threads:[~2009-07-24 13:16 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-07-24 7:53 [PATCH] x86: Use clflush() instead of wbinvd() whenever possible when changing mapping Thomas Hellstrom
2009-07-24 10:05 ` Andi Kleen
2009-07-24 10:21 ` Thomas Hellstrom
2009-07-24 10:58 ` Andi Kleen
2009-07-24 11:14 ` Thomas Hellstrom
2009-07-24 13:16 ` Andi Kleen [this message]
2009-07-30 9:07 ` Pavel Machek
2009-08-02 16:22 ` Thomas Hellström
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