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nohz: Prevent tilegx network driver interrupts

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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>
This commit is contained in:
Chris Metcalf 2015-07-10 15:37:25 -04:00 committed by Frederic Weisbecker
parent 2019e8a302
commit 03f6199a35
2 changed files with 12 additions and 1 deletions
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4
drivers/net/ethernet/tile/tilegx.c
View File

@ -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;
}

9
include/linux/tick.h
View File

@ -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