Commit 895ee6a2 authored by Yury Norov [NVIDIA]'s avatar Yury Norov [NVIDIA] Committed by Yury Norov
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topology: make for_each_node_with_cpus() O(N) 



for_each_node_with_cpus() calls nr_cpus_node() at every iteration, which
makes it O(N^2). Kernel tracks such nodes with N_CPU record in node_states
array. Switching to it makes for_each_node_with_cpus() O(N).

Andrea:

Now we can include also offline nodes with CPUs assigned (assuming it's
possible). If checking the online state is required, the user must use
node_online() within the loop.

CC: Andrea Righi <arighi@nvidia.com>
CC:Tejun Heo <tj@kernel.org>
Signed-off-by: default avatarYury Norov [NVIDIA] <yury.norov@gmail.com>
parent a256ae22

include/linux/nodemask.h

+1 −0
Original line number Diff line number Diff line
@@ -522,6 +522,7 @@ static __always_inline int node_random(const nodemask_t *maskp) 


#define for_each_node(node)	   for_each_node_state(node, N_POSSIBLE)

#define for_each_online_node(node) for_each_node_state(node, N_ONLINE)

#define for_each_node_with_cpus(node)	for_each_node_state(node, N_CPU)



/*

 * For nodemask scratch area.

include/linux/topology.h

+1 −4
Original line number Diff line number Diff line
@@ -29,6 +29,7 @@ 


#include <linux/arch_topology.h>

#include <linux/cpumask.h>

#include <linux/nodemask.h>

#include <linux/bitops.h>

#include <linux/mmzone.h>

#include <linux/smp.h>
@@ -39,10 +40,6 @@ 
#define nr_cpus_node(node) cpumask_weight(cpumask_of_node(node))

#endif



#define for_each_node_with_cpus(node)			\

	for_each_online_node(node)			\

		if (nr_cpus_node(node))



int arch_update_cpu_topology(void);



/* Conform to ACPI 2.0 SLIT distance definitions */