Jeff Atwood explains why Vista uses so much memory. "You have to stop thinking of system memory as a resource and start thinking of it as a a cache. Just like the level 1 and level 2 cache on your CPU, system memory is yet another type of high-speed cache that sits between your computer and the disk drive. And the most important rule of cache design is that empty cache memory is wasted cache memory. Empty cache isn't doing you any good. It's expensive, high-speed memory sucking down power for zero benefit. The primary mission in the life of every cache is to populate itself as quickly as possible with the data that's most likely to be needed - and to consistently deliver a high 'hit rate' of needed data retrieved from the cache."
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Member since:2005-07-08
First, I can't possibly figure out how that "it" I replaced could refer to SuperFetch or any similar technology because Linux doesn't have anticipatory page-in mechanism. Not in 2.4, not now, and probably not in the near future. In addition, memory is not a cache for paging space, so any attempt to associate SuperFetch with using memory as a disk cache is simply wrong.
SuperFetch has nothing to do with the disk cache, since it doesn't have anything to do with the filesystem. On the contrary, it is a virtual memory mechanism. It performs page-ins from the paging space before the virtual pages are referenced based on previously observed trends, replacing least-recently-used pages in memory with hopefully soon-to-be-used pages from paging space. SuperFetch doesn't change the fact that memory should always be full, nor does it create a magic way to page something in without paging something out. It doesn't minimize paging, either. In the best case scenario, it performs paging earlier than it would have otherwise occurred. In anything but the best case, it generates more paging operations than necessary.
I don't understand why you take offense to my comment. Anyone can argue the point of the article, but not that many people actually have the knowledge to decide for themselves whether the whole premise of the article is full of crap. I assumed that the article must be about a disk cache, since that's the only way the teaser makes sense. Memory is not a cache for paging space! When a page gets copied into memory, its blocks are freed on the disk's paging space. When filesystem data gets cached, it persists on the backing store. The whole premise of the article is wrong. So why should I argue it?
Member since:2005-07-10
This article is not about disk caching. It is about the benefits of SuperFetch, I don't know where you got the idea it was about disk caching, but you know what they say about people who assume.
Read the article, my comments were in context with the article. This is not a social forum. The comments are suppose to be focused on the article above. Try it sometime before jumping to major conclusions and you won't look like a troll.
Edited 2007-03-01 00:49
Member since:
2005-07-10
Wow did you totally miss the point. I never said Linux didn't have a disk cache, in fact if you actually read the article it was talking about the SuperFetch technology that tries to minimize disk cache.
And that is what I was referring to the actual process that minimizes the use of disk cache. But in order to understand the comments I made on the article you actually have to read the article.
And the very fact that you had to insert the words disk cache, to go off on a tangent about a sentence you took out of context. Shows me you had no intention of actually arguing the point of the article.
Edited 2007-02-28 22:57