From: Chuck Lever <cel@monkey.org>
To: "Stephen C. Tweedie" <sct@redhat.com>
Cc: linux-mm@kvack.org
Subject: Re: possible brw_page optimization
Date: Thu, 27 Jan 2000 13:50:23 -0500 (EST) [thread overview]
Message-ID: <Pine.BSO.4.10.10001271342110.20668-100000@funky.monkey.org> (raw)
In-Reply-To: <14479.33307.9093.845257@dukat.scot.redhat.com>
On Wed, 26 Jan 2000, Stephen C. Tweedie wrote:
> On Wed, 26 Jan 2000 11:02:37 -0500 (EST), Chuck Lever <cel@monkey.org>
> said:
> > however, somehow i'd have to guarantee that all buffers associated with a
> > page that is to be compressed/encrypted are read/written at once.
>
> Why? The swapper already does per-page IO locking, so you are protected
> against any conflicts while a page is being written out.
it's not a locking issue. the encryption algorithm is a block cipher on
the whole page. in order to decrypt a page, you need to be sure you have
all the pieces. you can't read parts of the page and decrypt them.
forgetting about encryption for a moment, you don't think the optimization
is useful in the general case? it's hardly ever used, if at all; plus it
seems to introduce some bugs. that code would be a lot cleaner without
all the bother. the "common case," by far, is to read/write the whole
page.
- Chuck Lever
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next prev parent reply other threads:[~2000-01-27 18:50 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2000-01-21 20:21 Chuck Lever
2000-01-26 13:01 ` Stephen C. Tweedie
2000-01-26 16:02 ` Chuck Lever
2000-01-26 23:24 ` Stephen C. Tweedie
2000-01-27 18:50 ` Chuck Lever [this message]
2000-01-27 19:52 ` Stephen C. Tweedie
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