Commit 03f6199a authored Jul 10, 2015 by Chris Metcalf Committed by Frederic Weisbecker Jul 29, 2015

nohz: Prevent tilegx network driver interrupts



Normally the tilegx networking shim sends irqs to all the cores
to distribute the load of processing incoming-packet interrupts,
so that you can get to multiple Gb's of traffic inbound.

However, in nohz_full mode we don't want to interrupt the
nohz_full cores by default, so we limit the set of cores we use
to only the online housekeeping cores.

To make client code easier to read, we introduce a new nohz_full
accessor, housekeeping_cpumask(), which returns a pointer to the
housekeeping_mask if nohz_full is enabled, and otherwise returns
the cpu_possible_mask.

Signed-off-by: Chris Metcalf <cmetcalf@ezchip.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>

parent 2019e8a3

drivers/net/ethernet/tile/tilegx.c

+3 −1

Original line number	Diff line number	Diff line
		@@ -40,6 +40,7 @@
		#include <linux/tcp.h>
		#include <linux/net_tstamp.h>
		#include <linux/ptp_clock_kernel.h>
		#include <linux/tick.h>

		#include <asm/checksum.h>
		#include <asm/homecache.h>
		@@ -2273,7 +2274,8 @@ static int __init tile_net_init_module(void)
		tile_net_dev_init(name, mac);

		if (!network_cpus_init())
		network_cpus_map = *cpu_online_mask;
		cpumask_and(&network_cpus_map, housekeeping_cpumask(),
		cpu_online_mask);

		return 0;
		}

include/linux/tick.h

+9 −0

Original line number	Diff line number	Diff line
		@@ -163,6 +163,15 @@ static inline void tick_nohz_full_kick_all(void) { }
		static inline void __tick_nohz_task_switch(struct task_struct *tsk) { }
		#endif

		static inline const struct cpumask *housekeeping_cpumask(void)
		{
		#ifdef CONFIG_NO_HZ_FULL
		if (tick_nohz_full_enabled())
		return housekeeping_mask;
		#endif
		return cpu_possible_mask;
		}

		static inline bool is_housekeeping_cpu(int cpu)
		{
		#ifdef CONFIG_NO_HZ_FULL

Admin message