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Comment by eliben | Hacker News Reader

The title of the link (unlike the linked page) suggests that Linux is somehow to blame here... Why? Using RAM for disk caching is a good thing.

Besides, this technique is employed by Windows as well. It's just that the average Windows user probably doesn't know how much free RAM his PC has (well, the really average user doesn't know how much total RAM it has). My Windows 7 box takes at least 2GB of memory to itself for disk caching, AFAIU.

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Windows started doing disk caching with Vista and users certainly noticed and complained in much the same way.

Windows didn't start doing disk caching with Vista. Perhaps it used memory more aggressively, or changed the way it did the accounting, but it certainly didn't start doing disk caching just with Vista, as anyone who remembers the difference in performance of DOS before and after running SMARTDRV will attest.

2000/XP was always extremely aggressive about allocating memory for cache. It would very often swap stuff out to increase available cache, which made the apps you did not use for just a few seconds completely unresponsive.

Specifically, minimized applications got their working set trimmed. You could see this in Task Manager: it's Memory Usage column was actually Working Set (I think they're more explicitly labelled these days) and it frequently went from many MB down to a few KB once you minimized the app. Working set is the set of pages, currently in memory, that the app has used "recently", and are thus less likely to be paged to disk. Shrinking the WS makes pages more likely to be paged out.

Windows started doing pre-emptive caching with Vista, based on the applications you tend to run.

I think the average user doesn't even know what RAM is. My neighbour, for example, doesn't know the distinction between the space available in RAM and the capacity of his harddisk. Which led to a strange misunderstanding when he told me his PC had '250 giga of internal memory'. I tried to explain than with 'internal memory' people usually mean something else, but I didn't think he understood. Never mind, he doesn't grasp hierarchical filesystems either, but all is fine as long as he can edit his photos (which in his perception are kept within Elements) and 'surf the internet'.

My apologies, that's certainly not what I meant to imply (and hence the use of the word seemingly). The point I was coming from was with regards to the number of times I've had to explain these concepts to an exasperated friend or cow-orker, when they've exclaimed something along the lines of "I've just looked at `top` and there's no free memory!".

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