Messages in this thread |  | | | Date | Sun, 28 Aug 2005 13:39:22 -0700 | | From | Andrew Morton <> | | Subject | Re: [PATCH] make radix tree gang lookup faster by using a bitmap search |
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Linus Torvalds <torvalds@osdl.org> wrote: > > > > On Sun, 28 Aug 2005, James Bottomley wrote: > > > > radix_tree_insert() is reliable from IRQ provided you don't try to use > > radix_tree_preload() and you defined your radix tree gfp flag to be > > GFP_ATOMIC. > > It would be better if it wasn't, though.
There's nothing in radix-tree which forces this: it requires caller-provided locking.
> I really don't see why we made it irq-safe, and take the hit of disabling > interrupts in addition to the locking. That's a quite noticeable loss, > and I don't think it's really a valid thing to insert (or look up) page > cache entries from interrupts. > > What _is_ it that makes us do that, btw? Is it just because we clear the > writeback tag bits or something? Sad. It makes page lookup noticeably more > expensive.
Yes, address_space.tree_lock was made IRQ-safe so we could alter the tree's tags from disk completions. Presumably Nick's lockless pagecache stuff removes that. - 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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