linux-kernel - Re: Improvement on memory subsystem

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Date:	Wed, 19 Jul 2006 11:44:27 +0800
From:	"yunfeng zhang" <zyf.zeroos@...il.com>
To:	"Valdis.Kletnieks@...edu" <Valdis.Kletnieks@...edu>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: Improvement on memory subsystem

> On Tue, 18 Jul 2006 18:03:54 +0800, yunfeng zhang said:
>
> But wouldn't that end up causing a seek storm, rather than handling the pages
> in the order that minimizes the total seek distance, no matter where they are
> in memory? Remember - if you have a 2Ghz processor, and a disk that seeks in 1
> millisecond, every seek is (*very* roughly) about 2 million instructions.  So
> if we can burn 20 thousand instructions finding a read order that eliminates
> *one* seek, we're 1.98M instructions ahead.

Further sample is showd below

to page-fault (page-in operation) scan the pte triggering page-fault and its
following ptes in its VMA, if its followers are swap_entry_t type and their
relative offset is enough closer to the host pte, read them together.

to swap daemon (page-out operation), let's scan every pte of a VMA in the OS, if
we find an appropriate candidate, lock it and its following ptes if all ptes are
appropriate swap-out objects, then allocate a consecutive swap pages from swap
space, if we're success, do an efficient asynchronous IO operation; if we're
failed, shrink those ptes.

Isn't it right?

By the way, all improvements listed by me are introduced briefly, most of them
are complex, maybe only my documentation can descript them clearly.
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