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Pagefaults
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I noticed this too - you can get the windows task manager to show page faults. Winamps was flying up, and a lot of apps were going up pretty steadily.
Is a page fault just a miss of cached memory?
Is a page fault just a miss of cached memory?
High level of page faults are usually indicative of poor temporal and spatial locality of memory access. Reducing page faults can be done by reducing your process''s working set within a given time frame. There are a multitude of different ways to do that. Off the top of my head: use custom allocators to group temporally local objects in spatially local memory address, change data structures to favor fewer total allocations, taking advantage of multiple heaps if your compiler supports them, pre-processing batched data fetchs to so that they occur in a spatial local manner, and of course, the just-use-less-memory technique.
quote:
Original post by jonr
Anyone tried using something like this? ...snip...
sounds like it can lock your memory so you dont get pagefaulting....
I find that in most cases VirtualLock() will actually hurt application performance. The OS tends to be a better judge of what needs to be paged out than the programmer.
quote:
Original post by Evil Steve
Is a page fault just a miss of cached memory?
A page fault is when memory requested is not in the physical memory, so the virtual memory manager needs to fetch the requested information from the disk and place in physical memory.
When the memory requested is not the cache, it''s simply called a cache miss.
If anything uses memory mapped files (WinAmp might) every 4k of data read off disk will result in a page fault.
I''m still sticking to what I said, use less memory.
find ways to do that, and the page faulting will disappear.
suggestions:
-optimize for size, not speed
-try to avoid referencing various large piles of data in tight loops, just try to stick to a minimal set.
-reduce quality of lossy things, like textures
find ways to do that, and the page faulting will disappear.
suggestions:
-optimize for size, not speed
-try to avoid referencing various large piles of data in tight loops, just try to stick to a minimal set.
-reduce quality of lossy things, like textures
What sort of performance hit does a page fault incur? 50ms? It might be small, but if you get a page fault every time you go through your main loop, that''ll slow things down a hell of a lot...
A page fault can''t possible take 50ms.. when working with virtual memory (usually by the OS), page faults occur all the time. IIRC from some online tutorial, the memory has to be swapped to disk, and when it needs to be accessed, it will generate a page fault to signal that it needs to be swapped to memory.
edit: Oh. SiCrane already said that.
edit: Oh. SiCrane already said that.
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