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Re: Restricted storage
From: |
Lluis |
Subject: |
Re: Restricted storage |
Date: |
Tue, 30 May 2006 01:14:13 +0200 |
User-agent: |
Mutt-ng devel-r804 (based on Mutt 1.5.11/2005-09-15) |
El Mon, May 29, 2006 at 06:28:02PM +0200, Pierre THIERRY ens deleità amb les
següents paraules:
> Scribit Bas Wijnen dies 29/05/2006 hora 14:28:
>>> I wonder if a write notice flag could be interesting.
>> Perhaps. I suspect that it will cost performance in situations where
>> it isn't used though, which is unacceptable IMO (because it will
>> hardly ever be used, I suppose).
>
> I'm pretty sure it can be built so that when not used, it has no impact.
> The notifier could be some sort of proxy, and it then it would just be
> absent when not used. In most cases, write notification would only be
> needed once (just to know when initial integrity is broken), and the
> system could be made to remove that proxy then.
As of what I know, a proxy could only play a role when a page fault occurs,
so it wouldn't be able to proxy _all_ accesses (and thus not all writes).
A compromise solution, which doesn't penalise the common case (no notice),
would be to use pages that are always on COW.
Although it would have a bad performance when used (but no zero penalty
when not used), it allows to capture all write accesses to the page and let
a "proxy" send the notice.
Read you,
Lluis
--
"And it's much the same thing with knowledge, for whenever you learn
something new, the whole world becomes that much richer."
-- The Princess of Pure Reason, as told by Norton Juster in The Phantom
Tollbooth
Listening: Dream Theater (Six Degrees Of Inner Turbulence - Disc One) - 3.
Misunderstood
Re: Restricted storage, Marcus Brinkmann, 2006/05/29
Re: Restricted storage, Pierre THIERRY, 2006/05/29
Re: Restricted storage, Jonathan S. Shapiro, 2006/05/30
Re: Restricted storage, Jonathan S. Shapiro, 2006/05/29
Re: Restricted storage, Jonathan S. Shapiro, 2006/05/30