17 Jan
2025
17 Jan
'25
1:21 a.m.
On 1/16/25 16:37, Ethan Zhao wrote:
hpa suggested to introduce "switch_likely" for this kind of optimization on a switch statement, which is also easier to read. I measured it with a user space focus test, it does improve performance a lot. But obviously there are still a lot of work to do.
Find a way to instruct compiler to pick the right hot branch meanwhile make folks reading happy... yup, a lot of work.
It's not that complicated, believe it or not.
/* * switch(v) biased for speed in the case v == l * * Note: gcc is quite sensitive to the exact form of this * expression. */ #define switch_likely(v,l) \ switch((__typeof__(v))__builtin_expect((v),(l)))
-hpa