sched: optimize effective_load()
s_i = S * rw_i / \Sum_j rw_j -> \Sum_j rw_j = S * rw_i / s_i -> s'_i = S * (rw_i + w) / (\Sum_j rw_j + w) delta s = s' - s = S * (rw + w) / ((S * rw / s) + w) = s * (S * (rw + w) / (S * rw + s * w) - 1) a = S*(rw+w), b = S*rw + s*w delta s = s * (a-b) / b IOW, trade one divide for two multiplies Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com> Cc: Mike Galbraith <efault@gmx.de> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Showing
Please register or sign in to comment