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[XFS] Add support for hotplug CPUs to the per-CPU superblock counters by

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registering a notifier callback that listens to CPU up/down events to
modify the counters appropriately.

SGI-PV: 949726
SGI-Modid: xfs-linux-melb:xfs-kern:25214a

Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Nathan Scott <nathans@sgi.com>
This commit is contained in:
David Chinner 2006-03-14 13:23:52 +11:00 committed by Nathan Scott
parent 2d0f864be3
commit e8234a6871
3 changed files with 76 additions and 3 deletions
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2
fs/xfs/linux-2.6/xfs_linux.h
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@ -73,6 +73,8 @@
#include <linux/list.h>
#include <linux/proc_fs.h>
#include <linux/sort.h>
#include <linux/cpu.h>
#include <linux/notifier.h>
#include <asm/page.h>
#include <asm/div64.h>

76
fs/xfs/xfs_mount.c
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@ -60,6 +60,7 @@ STATIC int xfs_icsb_modify_counters(xfs_mount_t *, xfs_sb_field_t,
int, int);
STATIC int xfs_icsb_modify_counters_locked(xfs_mount_t *, xfs_sb_field_t,
int, int);
STATIC int xfs_icsb_disable_counter(xfs_mount_t *, xfs_sb_field_t);
#else
@ -1716,9 +1717,72 @@ xfs_mount_log_sbunit(
* To ensure counters don't remain disabled, they are rebalanced when
* the global resource goes above a higher threshold (i.e. some hysteresis
* is present to prevent thrashing).
*
* Note: hotplug CPUs not yet supported
*/
/*
* hot-plug CPU notifier support.
*
* We cannot use the hotcpu_register() function because it does
* not allow notifier instances. We need a notifier per filesystem
* as we need to be able to identify the filesystem to balance
* the counters out. This is acheived by having a notifier block
* embedded in the xfs_mount_t and doing pointer magic to get the
* mount pointer from the notifier block address.
*/
STATIC int
xfs_icsb_cpu_notify(
struct notifier_block *nfb,
unsigned long action,
void *hcpu)
{
xfs_icsb_cnts_t *cntp;
xfs_mount_t *mp;
int s;
mp = (xfs_mount_t *)container_of(nfb, xfs_mount_t, m_icsb_notifier);
cntp = (xfs_icsb_cnts_t *)
per_cpu_ptr(mp->m_sb_cnts, (unsigned long)hcpu);
switch (action) {
case CPU_UP_PREPARE:
/* Easy Case - initialize the area and locks, and
* then rebalance when online does everything else for us. */
spin_lock_init(&cntp->icsb_lock);
cntp->icsb_icount = 0;
cntp->icsb_ifree = 0;
cntp->icsb_fdblocks = 0;
break;
case CPU_ONLINE:
xfs_icsb_balance_counter(mp, XFS_SBS_ICOUNT, 0);
xfs_icsb_balance_counter(mp, XFS_SBS_IFREE, 0);
xfs_icsb_balance_counter(mp, XFS_SBS_FDBLOCKS, 0);
break;
case CPU_DEAD:
/* Disable all the counters, then fold the dead cpu's
* count into the total on the global superblock and
* re-enable the counters. */
s = XFS_SB_LOCK(mp);
xfs_icsb_disable_counter(mp, XFS_SBS_ICOUNT);
xfs_icsb_disable_counter(mp, XFS_SBS_IFREE);
xfs_icsb_disable_counter(mp, XFS_SBS_FDBLOCKS);
mp->m_sb.sb_icount += cntp->icsb_icount;
mp->m_sb.sb_ifree += cntp->icsb_ifree;
mp->m_sb.sb_fdblocks += cntp->icsb_fdblocks;
cntp->icsb_icount = 0;
cntp->icsb_ifree = 0;
cntp->icsb_fdblocks = 0;
xfs_icsb_balance_counter(mp, XFS_SBS_ICOUNT, XFS_ICSB_SB_LOCKED);
xfs_icsb_balance_counter(mp, XFS_SBS_IFREE, XFS_ICSB_SB_LOCKED);
xfs_icsb_balance_counter(mp, XFS_SBS_FDBLOCKS, XFS_ICSB_SB_LOCKED);
XFS_SB_UNLOCK(mp, s);
break;
}
return NOTIFY_OK;
}
int
xfs_icsb_init_counters(
xfs_mount_t *mp)
@ -1730,6 +1794,10 @@ xfs_icsb_init_counters(
if (mp->m_sb_cnts == NULL)
return -ENOMEM;
mp->m_icsb_notifier.notifier_call = xfs_icsb_cpu_notify;
mp->m_icsb_notifier.priority = 0;
register_cpu_notifier(&mp->m_icsb_notifier);
for_each_online_cpu(i) {
cntp = (xfs_icsb_cnts_t *)per_cpu_ptr(mp->m_sb_cnts, i);
spin_lock_init(&cntp->icsb_lock);
@ -1746,8 +1814,10 @@ STATIC void
xfs_icsb_destroy_counters(
xfs_mount_t *mp)
{
if (mp->m_sb_cnts)
if (mp->m_sb_cnts) {
unregister_cpu_notifier(&mp->m_icsb_notifier);
free_percpu(mp->m_sb_cnts);
}
}

1
fs/xfs/xfs_mount.h
View File

@ -401,6 +401,7 @@ typedef struct xfs_mount {
#ifdef HAVE_PERCPU_SB
xfs_icsb_cnts_t *m_sb_cnts; /* per-cpu superblock counters */
unsigned long m_icsb_counters; /* disabled per-cpu counters */
struct notifier_block m_icsb_notifier; /* hotplug cpu notifier */
#endif
} xfs_mount_t;