linux-kernel - Re: [PATCH RFC/RFB] x86_64, i386: interrupt dispatch changes

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Message-ID: <20081105182615.GG7286@localhost>
Date:	Wed, 5 Nov 2008 21:26:15 +0300
From:	Cyrill Gorcunov <gorcunov@...il.com>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	Ingo Molnar <mingo@...e.hu>,
	Alexander van Heukelum <heukelum@...tmail.fm>,
	Andi Kleen <andi@...stfloor.org>,
	Alexander van Heukelum <heukelum@...lshack.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Thomas Gleixner <tglx@...utronix.de>, lguest@...abs.org,
	jeremy@...source.com, Steven Rostedt <srostedt@...hat.com>,
	Mike Travis <travis@....com>
Subject: Re: [PATCH RFC/RFB] x86_64, i386: interrupt dispatch changes

[H. Peter Anvin - Wed, Nov 05, 2008 at 10:20:23AM -0800]
| Cyrill Gorcunov wrote:
| > 
| > I see. Thanks! Btw Peter, I remember I read long time ago about
| > segment caches (well... in time of DOS programming actually). But
| > there was only 'common' words like this cache exist. But maybe
| > it's possible to know what exactly size of such a cache is?
| > You mentoined number 32. (heh... I hadn't remember it until
| > you mentoined about such a cache :-)
| > 
| 
| As with any other caching structure, you can discover its size,
| associativity, and replacement policy by artificially trying to provoke
| patterns that produce pathological timings.
| 
| At Transmeta, at one time we used a 32-entry direct-mapped cache, which
| ended up with a ~96% hit rate on common Win95 benchmarks.
| 
| I should, however, make it clear that there are other alternatives for
| speeding up segment descriptor loading, and not all of them rely on a cache.
| 
| 	-hpa
| 

Thanks a lot for explanation!

		- Cyrill -
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