Messages in this thread | | | From | Rusty Russell <> | Subject | Re: [PATCH 1/2] hw_random: core updates to allow more efficient drivers | Date | Tue, 1 Dec 2009 13:38:15 +1030 |
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On Tue, 1 Dec 2009 05:14:16 am Matt Mackall wrote: > On Mon, 2009-11-30 at 10:28 +0000, Ian Molton wrote: > > Rusty Russell wrote: > > > > > And might as well just #defube RNG_BUFFSIZE SMP_CACHE_BYTES (or use > > > SMP_CACHE_BYTES here and sizeof() elsewhere). > > > > This can lead to a rather small (4 byte) buffer on some systems, however > > I don't know if in practice a tiny buffer or a big one would be better > > for performance on those machines. I guess if its a problem someone can > > patch the code to allocate a minimum of (say) 16 bytes in future... > > Hmmm, I think this was bad advice from Rusty.
Me too. But really, it's because we're using cacheline alignment as a proxy for something else, and it's not a good fit.
But we're bikeshedding, so apply or revert.
/* A buffer which can hold any fundamental type: drivers are fussy. */ static u8 rng_buffer[SMP_CACHE_BYTES < 8 ? 8 : SMP_CACHE_BYTES] __cacheline_aligned;
Either way, both patches: Acked-by: Rusty Russell <rusty@rustcorp.com.au>
Thanks, Rusty.
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