Messages in this thread | | | Date | Wed, 25 Oct 2006 10:42:26 +0200 | From | Pavel Machek <> | Subject | Re: [PATCH] Use extents for recording what swap is allocated. |
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Hi!
> > > With the code I have in Suspend2 (which is what I'm working towards), > > > the value includes the swap_type, so there's no overlap. Assuming the > > > swap allocator does it's normal thing and swap allocated is contiguous, > > > you'll probably end up with two extents: one containing the swap > > > allocated on the first device, and the other containing the swap > > > allocated on the second device. So (with the current version), striping > > > would use 6 * sizeof(unsigned long) instead of 3 * sizeof(unsigned > > > long). > > > > And now, can you do same computation assuming the swap allocator goes > > completely crazy, and free space is in 1-page chunks? > > The worst case is 3 * sizeof(unsigned long) * > number_of_swap_extents_allocated bytes.
Okay, so if we got 4GB of swap space, thats 1MB swap pages, worst case is you have one extent per page, on x86-64 that's 24MB. +kmalloc overhead, I assume?
And you do linear walks over those extents, leading to O(n^2) algorithm, no? That has bitten us before... Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html - 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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