Messages in this thread | | | Date | Wed, 12 Sep 2018 06:14:33 +0000 | From | Kevin Easton <> | Subject | Re: [PATCH net-next v3 01/17] asm: simd context helper API |
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On Mon, Sep 10, 2018 at 07:08:21PM -0600, Jason A. Donenfeld wrote: > Sometimes it's useful to amortize calls to XSAVE/XRSTOR and the related > FPU/SIMD functions over a number of calls, because FPU restoration is > quite expensive. This adds a simple header for carrying out this pattern: > > simd_context_t simd_context = simd_get(); > while ((item = get_item_from_queue()) != NULL) { > encrypt_item(item, simd_context); > simd_context = simd_relax(simd_context); > } > simd_put(simd_context); > > The relaxation step ensures that we don't trample over preemption, and > the get/put API should be a familiar paradigm in the kernel.
Given that it's always supposed to be used like that, mightn't it be better if simd_relax() took a pointer to the context, so the call is just
simd_relax(&simd_context);
?
The inlining means that there won't actually be a pointer dereference in the emitted code.
If simd_put() also took a pointer then it could set the context back to HAVE_NO_SIMD as well?
- Kevin
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