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Fix CPU hotplug 

Allocate a kmem cache magazine for every possible CPU which might
be added to the system.  This ensures that when one of these CPUs
is enabled it can be safely used immediately.

For many systems the number of online CPUs is identical to the
number of present CPUs so this does imply an increased memory
footprint.  In fact, dynamically allocating the array of magazine
pointers instead of using the worst case NR_CPUS can end up
decreasing our memory footprint.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ned Bass <bass6@llnl.gov>
Closes #482
This commit is contained in:
Brian Behlendorf 2015-10-12 12:31:05 -07:00
parent 374303a3c9
commit 9b13f65d28
2 changed files with 8 additions and 9 deletions
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2
include/sys/kmem_cache.h
View File

@ -170,7 +170,7 @@ typedef struct spl_kmem_cache {
uint32_t skc_magic; /* Sanity magic */
uint32_t skc_name_size; /* Name length */
char *skc_name; /* Name string */
spl_kmem_magazine_t *skc_mag[NR_CPUS]; /* Per-CPU warm cache */
spl_kmem_magazine_t **skc_mag; /* Per-CPU warm cache */
uint32_t skc_mag_size; /* Magazine size */
uint32_t skc_mag_refill; /* Magazine refill count */
spl_kmem_ctor_t skc_ctor; /* Constructor */

15
module/spl/spl-kmem-cache.c
View File

@ -805,15 +805,18 @@ spl_magazine_create(spl_kmem_cache_t *skc)
if (skc->skc_flags & KMC_NOMAGAZINE)
return (0);
skc->skc_mag = kzalloc(sizeof (spl_kmem_magazine_t *) *
num_possible_cpus(), kmem_flags_convert(KM_SLEEP));
skc->skc_mag_size = spl_magazine_size(skc);
skc->skc_mag_refill = (skc->skc_mag_size + 1) / 2;
for_each_online_cpu(i) {
for_each_possible_cpu(i) {
skc->skc_mag[i] = spl_magazine_alloc(skc, i);
if (!skc->skc_mag[i]) {
for (i--; i >= 0; i--)
spl_magazine_free(skc->skc_mag[i]);
kfree(skc->skc_mag);
return (-ENOMEM);
}
}
@ -833,11 +836,13 @@ spl_magazine_destroy(spl_kmem_cache_t *skc)
if (skc->skc_flags & KMC_NOMAGAZINE)
return;
for_each_online_cpu(i) {
for_each_possible_cpu(i) {
skm = skc->skc_mag[i];
spl_cache_flush(skc, skm, skm->skm_avail);
spl_magazine_free(skm);
}
kfree(skc->skc_mag);
}
/*
@ -880,12 +885,6 @@ spl_kmem_cache_create(char *name, size_t size, size_t align,
might_sleep();
/*
* Allocate memory for a new cache and initialize it. Unfortunately,
* this usually ends up being a large allocation of ~32k because
* we need to allocate enough memory for the worst case number of
* cpus in the magazine, skc_mag[NR_CPUS].
*/
skc = kzalloc(sizeof (*skc), lflags);
if (skc == NULL)
return (NULL);