On 01.12.2016 20:51, Tom Herbert wrote:
>> > E.g. "mini-skb": Even if we assume that this provides a speedup
>> > (where does that come from? should make no difference if a 32 or
>> > 320 byte buffer gets allocated).
> It's the zero'ing of three cache lines. I believe we talked about that
> as netdev.
Jesper and me played with that again very recently:
In micro-benchmarks we saw a pretty good speed up not using the rep
stosb generated by gcc builtin but plain movq's. Probably the cost model
for __builtin_memset in gcc is wrong?
When Jesper is free we wanted to benchmark this and maybe come up with a
arch specific way of cleaning if it turns out to really improve throughput.
SIMD instructions seem even faster but the kernel_fpu_begin/end() kill
all the benefits.