Re: Improvement on memory subsystem

From: yunfeng zhang
Date: Tue Jul 18 2006 - 23:43:42 EST

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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