getcpu() call appears not to work
wingo opened this issue · comments
If I getcpu().cpu within a process run with taskset -c 6, it returns 0 for me. However if I S.sched_getaffinity(), that correctly returns the equivalent of {6}.
Hmm, what does strace say?
The behaviour is the same in the ljsyscall with Snabb as with current master ( 214550a ).
cat cputestscript.lua
local S = require("syscall")
print("getcpu", S.getcpu().cpu )
print("sched aff", S.sched_getaffinity())
strace taskset -c 3 luajit cputestscript.lua
Strace output includes:
getcpu([0], [0], 0) = 0
sched_getaffinity(0, 128, {8, 0, 0, 0}) = 32
The program prints:
getcpu 0
sched aff {3}
I've PR'd a fix - #195 - the problem was basically a typo in the source code ('node' was being given as an argument twice to getcpu, rather than cpu and node being given once each.)
Very nice, @kbara! I stared at that for some time and couldn't figure it out :)
merged, so closing this.