linux-kernel - Re: [PATCH] x86: Use clflush() instead of wbinvd() whenever possible when changing mapping

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Message-ID: <87ocra1jn6.fsf@basil.nowhere.org>
Date:	Fri, 24 Jul 2009 12:05:01 +0200
From:	Andi Kleen <andi@...stfloor.org>
To:	Thomas Hellstrom <thellstrom@...are.com>
Cc:	linux-kernel@...r.kernel.org, mingo@...e.hu,
	venkatesh.pallipadi@...el.com
Subject: Re: [PATCH] x86: Use clflush() instead of wbinvd() whenever possible when changing mapping

Thomas Hellstrom <thellstrom@...are.com> writes:

> The current code uses wbinvd() when the area to flush is > 4MB. Although this
> may be faster than using clflush() the effect of wbinvd() on irq latencies
> may be catastrophical on systems with large caches. Therefore use clflush()

may be? You seem to miss some hard data here.

I wouldn't expect wbinvd to take longer than a ms or two, which 
is probably not catastrophic yet.

-Andi

-- 
ak@...ux.intel.com -- Speaking for myself only.
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