On Fri, 29 Mar 2019 17:16:08 -0700, Alexei Starovoitov wrote: > With large verifier speed improvement brought by the previous patch > mark_reg_read() becomes the hottest function during verification. > On a typical program it consumes 40% of cpu. > mark_reg_read() walks parentage chain of registers to mark parents as LIVE_READ. > Once the register is marked there is no need to remark it again in the future. > Hence stop walking the chain once first LIVE_READ is seen. > This optimization drops mark_reg_read() time from 40% of cpu to <1% > and overall 2x improvement of verification speed. > For some programs the longest_mark_read_walk counter improves from ~500 to ~5 > > Signed-off-by: Alexei Starovoitov <ast@xxxxxxxxxx> Reviewed-by: Jakub Kicinski <jakub.kicinski@xxxxxxxxxxxxx>
