Eliminate binary.Read in instruction (un)marshaler #532
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ti-mo
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brycekahle
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A 64-bit immediate value was chosen to test the worst-case scenario, covering the entire function body of ins.Marshal() and Unmarshal(). Signed-off-by: Timo Beckers <timo@isovalent.com>
This patch introduces a hand-written (un)marshaler for asm.Instruction and eliminates the struct bpfInstruction wire format. This saves on a few allocs and shaves off about ~85% of CPU time spent (un)marshaling on my machine. name old time/op new time/op delta Read64bitImmediate-16 479ns ±12% 74ns ± 1% -84.62% (p=0.008 n=5+5) Write64BitImmediate-16 417ns ±10% 63ns ± 2% -84.97% (p=0.008 n=5+5) name old alloc/op new alloc/op delta Read64bitImmediate-16 32.0B ± 0% 8.0B ± 0% -75.00% (p=0.008 n=5+5) Write64BitImmediate-16 24.0B ± 0% 8.0B ± 0% -66.67% (p=0.008 n=5+5) name old allocs/op new allocs/op delta Read64bitImmediate-16 4.00 ± 0% 1.00 ± 0% -75.00% (p=0.008 n=5+5) Write64BitImmediate-16 3.00 ± 0% 1.00 ± 0% -66.67% (p=0.008 n=5+5) Signed-off-by: Timo Beckers <timo@isovalent.com>
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This still needs to be fuzzed, but the gains are nice so far:
The use of
internal.DiscardZeroes{}was considered for checking for64bit immediate has non-zero fields, but ended up being a lot slower than just including those bits in the read. The fact that it aligns with a single u32 interpretation is quite convenient. :)