linux-kernel - Re: Can context switches be faster?

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Message-Id: <200610131258.15451.ajwade@cpe001346162bf9-cm0011ae8cd564.cpe.net.cable.rogers.com>
Date:	Fri, 13 Oct 2006 12:56:42 -0400
From:	Andrew James Wade <andrew.j.wade@...il.com>
To:	John Richard Moser <nigelenki@...cast.net>
Cc:	andrew.j.wade@...il.com, Phillip Susi <psusi@....rr.com>,
	linux-kernel@...r.kernel.org
Subject: Re: Can context switches be faster?

On Friday 13 October 2006 01:29, John Richard Moser wrote:
> True.  You can trick the MMU into faulting into the kernel (PaX does
> this to apply non-executable pages-- pages, not halves of VM-- on x86),

Oooh, that is a neat hack!

> but it's orders of magnitude slower as I understand and the petty gains
> you can get over the hardware MMU doing it are not going to outweigh it.

It's architecture-dependent; not all architectures are even capeable of
walking the page table trees in hardware. They compensate with
lightweight traps for TLB cache misses. 

Andrew Wade
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