Messages in this thread | ![/](/images/icornerl.gif) | | From | Rusty Russell <> | Subject | Re: module changes | Date | Wed, 19 Feb 2003 15:28:52 +1100 |
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In message <20030218195140.27b0798f.akpm@digeo.com> you write: > Rusty Russell <rusty@rustcorp.com.au> wrote: > > The problem is that then you have to have to know whether this is a > > per-cpu thing created in a module, or not, when you use it 8( > > > > There are two things we can use to alleviate the problem. The first > > would be to put a minimal cap on the per-cpu data size (eg. 8k). The > > other possibility is to allocate on an object granularity, in which > > case the rule becomes "no single per-cpu object can be larger than > > XXX", but the cost is to write a mini allocator. > > > > Is kmalloc_percpu() not suitable?
Unfortunately, no. You have to use the same offsets as the in-kernel DEFINE_PER_CPU declarations, meaning that each cpu's stuff needs to be "sizeof kernel per-cpu-section" apart.
Which means an allocator which keeps a linked list of NR_CPUS * sizeof kernel-per-cpu-section things, and allocs and frees from that.
Hence this patch just tacks it on the end of the module, rather than deal with an allocator. A minor improvement would be only to allocate for the maximum possible CPU, which means about 6k * numcpus per module which declares per-cpu data, which is probably fine.
Rusty. -- Anyone who quotes me in their sig is an idiot. -- Rusty Russell. - 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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