[PATCH] shrink mmtimer memory size

This greatly reduces the amount of memory used by mmtimer on smaller
machines with large values of MAX_COMPACT_NODES.

Signed-off-by: Dimitri Sivanich <sivanich@sgi.com>
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/drivers/char/mmtimer.c b/drivers/char/mmtimer.c
index 78c89a3..c923781 100644 (file)
--- a/drivers/char/mmtimer.c
+++ b/drivers/char/mmtimer.c
@@ -1,11 +1,11 @@
 /*
- * Intel Multimedia Timer device implementation for SGI SN platforms.
+ * Timer device implementation for SGI SN platforms.
  *
  * This file is subject to the terms and conditions of the GNU General Public
  * License.  See the file "COPYING" in the main directory of this archive
  * for more details.
  *
- * Copyright (c) 2001-2004 Silicon Graphics, Inc.  All rights reserved.
+ * Copyright (c) 2001-2006 Silicon Graphics, Inc.  All rights reserved.
  *
  * This driver exports an API that should be supportable by any HPET or IA-PC
  * multimedia timer.  The code below is currently specific to the SGI Altix
@@ -45,7 +45,7 @@ MODULE_LICENSE("GPL");
 /* name of the device, usually in /dev */
 #define MMTIMER_NAME "mmtimer"
 #define MMTIMER_DESC "SGI Altix RTC Timer"
-#define MMTIMER_VERSION "2.0"
+#define MMTIMER_VERSION "2.1"
 
 #define RTC_BITS 55 /* 55 bits for this implementation */
 
@@ -227,10 +227,7 @@ typedef struct mmtimer {
        struct tasklet_struct tasklet;
 } mmtimer_t;
 
-/*
- * Total number of comparators is comparators/node * MAX nodes/running kernel
- */
-static mmtimer_t timers[NUM_COMPARATORS*MAX_COMPACT_NODES];
+static mmtimer_t ** timers;
 
 /**
  * mmtimer_ioctl - ioctl interface for /dev/mmtimer
@@ -441,29 +438,29 @@ static irqreturn_t
 mmtimer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
 {
        int i;
-       mmtimer_t *base = timers + cpu_to_node(smp_processor_id()) *
-                                               NUM_COMPARATORS;
        unsigned long expires = 0;
        int result = IRQ_NONE;
+       unsigned indx = cpu_to_node(smp_processor_id());
 
        /*
         * Do this once for each comparison register
         */
        for (i = 0; i < NUM_COMPARATORS; i++) {
+               mmtimer_t *base = timers[indx] + i;
                /* Make sure this doesn't get reused before tasklet_sched */
-               spin_lock(&base[i].lock);
-               if (base[i].cpu == smp_processor_id()) {
-                       if (base[i].timer)
-                               expires = base[i].timer->it.mmtimer.expires;
+               spin_lock(&base->lock);
+               if (base->cpu == smp_processor_id()) {
+                       if (base->timer)
+                               expires = base->timer->it.mmtimer.expires;
                        /* expires test won't work with shared irqs */
                        if ((mmtimer_int_pending(i) > 0) ||
                                (expires && (expires < rtc_time()))) {
                                mmtimer_clr_int_pending(i);
-                               tasklet_schedule(&base[i].tasklet);
+                               tasklet_schedule(&base->tasklet);
                                result = IRQ_HANDLED;
                        }
                }
-               spin_unlock(&base[i].lock);
+               spin_unlock(&base->lock);
                expires = 0;
        }
        return result;
@@ -523,7 +520,7 @@ static int sgi_timer_del(struct k_itimer *timr)
 {
        int i = timr->it.mmtimer.clock;
        cnodeid_t nodeid = timr->it.mmtimer.node;
-       mmtimer_t *t = timers + nodeid * NUM_COMPARATORS +i;
+       mmtimer_t *t = timers[nodeid] + i;
        unsigned long irqflags;
 
        if (i != TIMER_OFF) {
@@ -609,11 +606,11 @@ static int sgi_timer_set(struct k_itimer *timr, int flags,
        preempt_disable();
 
        nodeid =  cpu_to_node(smp_processor_id());
-       base = timers + nodeid * NUM_COMPARATORS;
 retry:
        /* Don't use an allocated timer, or a deleted one that's pending */
        for(i = 0; i< NUM_COMPARATORS; i++) {
-               if (!base[i].timer && !base[i].tasklet.state) {
+               base = timers[nodeid] + i;
+               if (!base->timer && !base->tasklet.state) {
                        break;
                }
        }
@@ -623,14 +620,14 @@ retry:
                return -EBUSY;
        }
 
-       spin_lock_irqsave(&base[i].lock, irqflags);
+       spin_lock_irqsave(&base->lock, irqflags);
 
-       if (base[i].timer || base[i].tasklet.state != 0) {
-               spin_unlock_irqrestore(&base[i].lock, irqflags);
+       if (base->timer || base->tasklet.state != 0) {
+               spin_unlock_irqrestore(&base->lock, irqflags);
                goto retry;
        }
-       base[i].timer = timr;
-       base[i].cpu = smp_processor_id();
+       base->timer = timr;
+       base->cpu = smp_processor_id();
 
        timr->it.mmtimer.clock = i;
        timr->it.mmtimer.node = nodeid;
@@ -645,11 +642,11 @@ retry:
                }
        } else {
                timr->it.mmtimer.expires -= period;
-               if (reschedule_periodic_timer(base+i))
+               if (reschedule_periodic_timer(base))
                        err = -EINVAL;
        }
 
-       spin_unlock_irqrestore(&base[i].lock, irqflags);
+       spin_unlock_irqrestore(&base->lock, irqflags);
 
        preempt_enable();
 
@@ -675,6 +672,7 @@ static struct k_clock sgi_clock = {
 static int __init mmtimer_init(void)
 {
        unsigned i;
+       cnodeid_t node, maxn = -1;
 
        if (!ia64_platform_is("sn2"))
                return -1;
@@ -691,14 +689,6 @@ static int __init mmtimer_init(void)
        mmtimer_femtoperiod = ((unsigned long)1E15 + sn_rtc_cycles_per_second /
                               2) / sn_rtc_cycles_per_second;
 
-       for (i=0; i< NUM_COMPARATORS*MAX_COMPACT_NODES; i++) {
-               spin_lock_init(&timers[i].lock);
-               timers[i].timer = NULL;
-               timers[i].cpu = 0;
-               timers[i].i = i % NUM_COMPARATORS;
-               tasklet_init(&timers[i].tasklet, mmtimer_tasklet, (unsigned long) (timers+i));
-       }
-
        if (request_irq(SGI_MMTIMER_VECTOR, mmtimer_interrupt, SA_PERCPU_IRQ, MMTIMER_NAME, NULL)) {
                printk(KERN_WARNING "%s: unable to allocate interrupt.",
                        MMTIMER_NAME);
@@ -712,6 +702,40 @@ static int __init mmtimer_init(void)
                return -1;
        }
 
+       /* Get max numbered node, calculate slots needed */
+       for_each_online_node(node) {
+               maxn = node;
+       }
+       maxn++;
+
+       /* Allocate list of node ptrs to mmtimer_t's */
+       timers = kmalloc(sizeof(mmtimer_t *)*maxn, GFP_KERNEL);
+       if (timers == NULL) {
+               printk(KERN_ERR "%s: failed to allocate memory for device\n",
+                               MMTIMER_NAME);
+               return -1;
+       }
+
+       /* Allocate mmtimer_t's for each online node */
+       for_each_online_node(node) {
+               timers[node] = kmalloc_node(sizeof(mmtimer_t)*NUM_COMPARATORS, GFP_KERNEL, node);
+               if (timers[node] == NULL) {
+                       printk(KERN_ERR "%s: failed to allocate memory for device\n",
+                               MMTIMER_NAME);
+                       return -1;
+               }
+               for (i=0; i< NUM_COMPARATORS; i++) {
+                       mmtimer_t * base = timers[node] + i;
+
+                       spin_lock_init(&base->lock);
+                       base->timer = NULL;
+                       base->cpu = 0;
+                       base->i = i;
+                       tasklet_init(&base->tasklet, mmtimer_tasklet,
+                               (unsigned long) (base));
+               }
+       }
+
        sgi_clock_period = sgi_clock.res = NSEC_PER_SEC / sn_rtc_cycles_per_second;
        register_posix_clock(CLOCK_SGI_CYCLE, &sgi_clock);