Messages in this thread | | | Date | Mon, 14 Aug 2006 15:46:16 +0400 | From | Evgeniy Polyakov <> | Subject | Re: [PATCH 1/1] network memory allocator. |
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On Mon, Aug 14, 2006 at 01:40:21PM +0200, Andi Kleen (ak@suse.de) wrote: > Evgeniy Polyakov <johnpol@2ka.mipt.ru> writes: > > > Design notes. > > Original idea was to store meta information used for allocation in an > > AVL tree [1], but since I found a way to use some "unused" fields in struct page, > > tree is unused in the allocator. > > But there seems to be still an AVL tree in there?
Yep. Tree structure can be used for simpler memory addon/removal from hotplug, but I have not that in mind. It will be removed soon.
> > Benchmarks with trivial epoll based web server showed noticeble (more > > than 40%) imrovements of the request rates (1600-1800 requests per > > second vs. more than 2300 ones). It can be described by more > > cache-friendly freeing algorithm, by tighter objects packing and thus > > reduced cache line ping-pongs, reduced lookups into higher-layer caches > > and so on. > > So what are its drawbacks compared to slab/kmalloc?
Hmm... Bigger per-page overhead (additional bitmask of free/used objects). More complex algorithm behind freeing.
> Also if it really performs that much better it might be a good > idea to replace all of kmalloc() with it, but doing that > would require a lot more benchmarks with various workloads > and small and big machines first.
First user can be MMU-less systems which suffer noticebly from fragmentations and power-of-two overhead.
> -Andi
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