tomcat-users mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Casper Wandahl Schmidt" <kalle.pri...@gmail.com>
Subject RE: [OT]RE: Maximum memory that can be assigned to Tomcat on windows platform
Date Thu, 01 Dec 2011 11:34:46 GMT


-----Original Message-----
From: Francis GALIEGUE [mailto:fge@one2team.com] 
Sent: 1. december 2011 12:33
To: Tomcat Users List
Subject: Re: [OT]RE: Maximum memory that can be assigned to Tomcat on windows platform

On Thu, Dec 1, 2011 at 12:29, Casper Wandahl Schmidt <kalle.privat@gmail.com> wrote:
[...]
>
> That didn't quite help me understand, because how can the OS map from ie.
> 0-4GB to 4-8GB (the window is moved) when it can only use a 32bit 
> register to tell the machine where to look in the psysical memory, 
> that is where my knowledge ends :) So I read about PAE and found out 
> that it uses 2 registers
> (36 bits due to some bits being used as flags) and that makes good 
> sense, but how can the cpu calculate an address without overflow and 
> send a command to the bus containing a 36bit address (or whatever 
> fetches the bits from RAM)? That is where I'm puzzled but I guess it 
> is because I'm not at all into ISA-level and below :)
>

It is the role of the MMU to do that. At any one time, it can map a "virtual", 32-bit wide,
address to a "real", 36-bit wide address. It uses TLBs (Translation Lookaside Buffers) for
that, and it is the OS'
role to have the correct TLB in place at any time.

Nice to know :) That explained it all :)

-Casper

--
Francis Galiegue
ONE2TEAM
Ingénieur système
Mob : +33 (0) 683 877 875
Tel : +33 (0) 178 945 552
fge@one2team.com
40 avenue Raymond Poincaré
75116 Paris

---------------------------------------------------------------------
To unsubscribe, e-mail: users-unsubscribe@tomcat.apache.org
For additional commands, e-mail: users-help@tomcat.apache.org



---------------------------------------------------------------------
To unsubscribe, e-mail: users-unsubscribe@tomcat.apache.org
For additional commands, e-mail: users-help@tomcat.apache.org


Mime
View raw message