Messages in this thread | | | From | Hans Georg Zezschwitz <> | Subject | Linux 1.3.90 vasts memory? | Date | Wed, 17 Apr 1996 12:24:33 +0200 (MET DST) |
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Hi,
probably this is my very own personal problem (starting once with a ZX-81 having 1 kB of RAM):
In 1.3.90 yet another element was introduced to the mem_map-structure:
In mm.h:
+ unsigned long map_nr; /* page->map_nr = page - mem_map */
Well, isn't it like that, that in result for every 4k / 8k page another 4 bytes are used? (-> 0,1 % of RAM is lost?). Sounds less, but thats 4 more pages on the average 16 MB system.
What are the benefits of that? I took a quick look through the code and my impression is, that it will mostly save a substraction and division (integer) when
- finding a free page - allocating a block from a file
Sure, that it is worth this? You could call it an optimization for speed vs. memory, but every modern OS an optimization for memory is a optimization for speed on the average system, too.
Sorry, probably the whole thing isn't worth these lines, but I felt all the time a little bit sick during the 1.3.x developement when "just a few" other elements for "struct vm_area" or "mem_map" where introduced.
Greetings,
Georg
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