Xen: reduce memory required for cpu_evtchn_mask
Impact: reduce memory usage.
Reduce this significant gain in the amount of memory used
when NR_CPUS bumped from 128 to 4096 by allocating the
array based on nr_cpu_ids:
65536 +2031616 2097152 +3100% cpu_evtchn_mask(.bss)
Signed-off-by: Mike Travis <travis@sgi.com>
Cc: Jeremy Fitzhardinge <jeremy@xensource.com>
Cc: Chris Wright <chrisw@sous-sol.org>
Cc: virtualization@lists.osdl.org
Cc: xen-devel@lists.xensource.com
diff --git a/drivers/xen/events.c b/drivers/xen/events.c
index e0767ff..ed7527b 100644
--- a/drivers/xen/events.c
+++ b/drivers/xen/events.c
@@ -75,7 +75,14 @@
static int evtchn_to_irq[NR_EVENT_CHANNELS] = {
[0 ... NR_EVENT_CHANNELS-1] = -1
};
-static unsigned long cpu_evtchn_mask[NR_CPUS][NR_EVENT_CHANNELS/BITS_PER_LONG];
+struct cpu_evtchn_s {
+ unsigned long bits[NR_EVENT_CHANNELS/BITS_PER_LONG];
+};
+static struct cpu_evtchn_s *cpu_evtchn_mask_p;
+static inline unsigned long *cpu_evtchn_mask(int cpu)
+{
+ return cpu_evtchn_mask_p[cpu].bits;
+}
static u8 cpu_evtchn[NR_EVENT_CHANNELS];
/* Reference counts for bindings to IRQs. */
@@ -115,7 +122,7 @@
unsigned int idx)
{
return (sh->evtchn_pending[idx] &
- cpu_evtchn_mask[cpu][idx] &
+ cpu_evtchn_mask(cpu)[idx] &
~sh->evtchn_mask[idx]);
}
@@ -128,8 +135,8 @@
cpumask_copy(irq_to_desc(irq)->affinity, cpumask_of(cpu));
#endif
- __clear_bit(chn, cpu_evtchn_mask[cpu_evtchn[chn]]);
- __set_bit(chn, cpu_evtchn_mask[cpu]);
+ __clear_bit(chn, cpu_evtchn_mask(cpu_evtchn[chn]));
+ __set_bit(chn, cpu_evtchn_mask(cpu));
cpu_evtchn[chn] = cpu;
}
@@ -147,7 +154,7 @@
#endif
memset(cpu_evtchn, 0, sizeof(cpu_evtchn));
- memset(cpu_evtchn_mask[0], ~0, sizeof(cpu_evtchn_mask[0]));
+ memset(cpu_evtchn_mask(0), ~0, sizeof(cpu_evtchn_mask(0)));
}
static inline unsigned int cpu_from_evtchn(unsigned int evtchn)
@@ -822,6 +829,10 @@
void __init xen_init_IRQ(void)
{
int i;
+ size_t size = nr_cpu_ids * sizeof(struct cpu_evtchn_s);
+
+ cpu_evtchn_mask_p = kmalloc(size, GFP_KERNEL);
+ BUG_ON(cpu_evtchn_mask == NULL);
init_evtchn_cpu_bindings();