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dynticks: avoid flow_cache_flush() interrupting every core

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Previously, if you did an "ifconfig down" or similar on one core, and
the kernel had CONFIG_XFRM enabled, every core would be interrupted to
check its percpu flow list for items that could be garbage collected.

With this change, we generate a mask of cores that actually have any
percpu items, and only interrupt those cores.  When we are trying to
isolate a set of cpus from interrupts, this is important to do.

Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Chris Metcalf 2013-03-19 11:35:58 +00:00 committed by David S. Miller
parent 7fa6f34081
commit 8fdc929f57
1 changed files with 39 additions and 3 deletions
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42
net/core/flow.c
View file

@ -323,6 +323,24 @@ static void flow_cache_flush_tasklet(unsigned long data)
complete(&info->completion);
}
/*
* Return whether a cpu needs flushing. Conservatively, we assume
* the presence of any entries means the core may require flushing,
* since the flow_cache_ops.check() function may assume it's running
* on the same core as the per-cpu cache component.
*/
static int flow_cache_percpu_empty(struct flow_cache *fc, int cpu)
{
struct flow_cache_percpu *fcp;
int i;
fcp = &per_cpu(*fc->percpu, cpu);
for (i = 0; i < flow_cache_hash_size(fc); i++)
if (!hlist_empty(&fcp->hash_table[i]))
return 0;
return 1;
}
static void flow_cache_flush_per_cpu(void *data)
{
struct flow_flush_info *info = data;
@ -337,22 +355,40 @@ void flow_cache_flush(void)
{
struct flow_flush_info info;
static DEFINE_MUTEX(flow_flush_sem);
cpumask_var_t mask;
int i, self;
/* Track which cpus need flushing to avoid disturbing all cores. */
if (!alloc_cpumask_var(&mask, GFP_KERNEL))
return;
cpumask_clear(mask);
/* Don't want cpus going down or up during this. */
get_online_cpus();
mutex_lock(&flow_flush_sem);
info.cache = &flow_cache_global;
atomic_set(&info.cpuleft, num_online_cpus());
for_each_online_cpu(i)
if (!flow_cache_percpu_empty(info.cache, i))
cpumask_set_cpu(i, mask);
atomic_set(&info.cpuleft, cpumask_weight(mask));
if (atomic_read(&info.cpuleft) == 0)
goto done;
init_completion(&info.completion);
local_bh_disable();
smp_call_function(flow_cache_flush_per_cpu, &info, 0);
flow_cache_flush_tasklet((unsigned long)&info);
self = cpumask_test_and_clear_cpu(smp_processor_id(), mask);
on_each_cpu_mask(mask, flow_cache_flush_per_cpu, &info, 0);
if (self)
flow_cache_flush_tasklet((unsigned long)&info);
local_bh_enable();
wait_for_completion(&info.completion);
done:
mutex_unlock(&flow_flush_sem);
put_online_cpus();
free_cpumask_var(mask);
}
static void flow_cache_flush_task(struct work_struct *work)