From: Jeremy Fitzhardinge <jeremy@goop.org>
To: xu feng <xu_feng_xu@yahoo.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: virtual cache, TLB, and OS
Date: Sat, 09 Dec 2006 21:15:22 -0800 [thread overview]
Message-ID: <457B97EA.3080609@goop.org> (raw)
In-Reply-To: <20061210022951.440.qmail@web58306.mail.re3.yahoo.com>
xu feng wrote:
> I am just confused about the author:
> 1- first point, why the cache has to be bothered by
> the change in the address logical-physical mapping
> since it is a virtual cache??
>
If you:
1. mmap file A at virtual address X
2. use memory at X
3. mmap file B at X
4. look at X
If its a virtual cache, and it wasn't flushed at step 3, then step 4
will see A's contents rather than B's.
> 2- could you please give me a situation where two
> virtual addresses from the same process are mapped to
> the same physical address?
>
> i can't see this happening since each process page is
> allocated a dedicated frame.
>
If you mmap a file multiple times, then the kernel will assign multiple
different virtual addresses for the same page cache page(s).
J
prev parent reply other threads:[~2006-12-10 5:15 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-12-10 2:29 virtual cache, TLB, and OS xu feng
2006-12-10 5:15 ` Jeremy Fitzhardinge [this message]
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