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Buddy Lumpkin wrote: >>>That's true, but it's not a magical property of swap space >>>- extra physical >>>RAM would do more or less the same thing. >>> > > >>Well it is a magical property of swap space, because extra RAM >>doesn't allow you to replace unused memory with often used memory. > > >>The theory holds true no matter how much RAM you have. Swap can >>improve performance. It can be trivially demonstrated. > > > I bet you have demonstrated this. It strikes me of an observation that could > be made in a lab environment. But your failing to realize that: > > 1) you will fill physical memory with pages eventually or your not doing > work. > > 2) pages do not just silently move to the swap device. They move as a result > of a memory shortfall > > 3) once physical memory is full, file system I/O will only benefit from > reads that incur a minor fault. All other file system operations are bound > by the rate you can reclaim pages from physical memory. > No, typically we can reclaim memory very quickly and the operations are bound by the speed of the block device. > 4) non-filesystem backed pages are still effected the same way, nothing has > changed. When you run your next filesystem related operation, those pages > will be faulted into physical memory, and something will be evicted to it's > backing store (remember, memory is full). > I haven't failed to realise 1, 2 or 4 and I don't know what you are arguing about. All I said was basically "no matter how much ram you have, swap can increase performance by allowing unused anonymous memory to be paged out, thereby increasing your maximum effective RAM". - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ | ||||||||||||
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