diff options
author | Waiman Long <longman@redhat.com> | 2017-02-08 10:44:15 +1100 |
---|---|---|
committer | Stephen Rothwell <sfr@canb.auug.org.au> | 2017-02-09 17:01:39 +1100 |
commit | 1842d91b7b4c6be23064b6601127293173aa750c (patch) | |
tree | 174a084a5068489ab7030227c231fe6f7d0e3124 /drivers/usb/usbip/usbip_common.c | |
parent | adf0206f053cc0bfb4b8e7ddb4ef81b9ecfdd99e (diff) |
debugobjects: reduce contention on the global pool_lock
On a large SMP system with many CPUs, the global pool_lock may become a
performance bottleneck as all the CPUs that need to allocate or free debug
objects have to take the lock. That can sometimes cause soft lockups
like:
NMI watchdog: BUG: soft lockup - CPU#35 stuck for 22s! [rcuos/1:21]
...
RIP: 0010:[<ffffffff817c216b>] [<ffffffff817c216b>]
_raw_spin_unlock_irqrestore+0x3b/0x60
...
Call Trace:
[<ffffffff813f40d1>] free_object+0x81/0xb0
[<ffffffff813f4f33>] debug_check_no_obj_freed+0x193/0x220
[<ffffffff81101a59>] ? trace_hardirqs_on_caller+0xf9/0x1c0
[<ffffffff81284996>] ? file_free_rcu+0x36/0x60
[<ffffffff81251712>] kmem_cache_free+0xd2/0x380
[<ffffffff81284960>] ? fput+0x90/0x90
[<ffffffff81284996>] file_free_rcu+0x36/0x60
[<ffffffff81124c23>] rcu_nocb_kthread+0x1b3/0x550
[<ffffffff81124b71>] ? rcu_nocb_kthread+0x101/0x550
[<ffffffff81124a70>] ? sync_exp_work_done.constprop.63+0x50/0x50
[<ffffffff810c59d1>] kthread+0x101/0x120
[<ffffffff81101a59>] ? trace_hardirqs_on_caller+0xf9/0x1c0
[<ffffffff817c2d32>] ret_from_fork+0x22/0x50
To reduce the amount of contention on the pool_lock, the actual
kmem_cache_free() of the debug objects will be delayed if the pool_lock is
busy. This will temporarily increase the amount of free objects available
at the free pool when the system is busy. As a result, the number of
kmem_cache allocation and freeing should be reduced.
This patch also groups the freeing of debug objects in a batch of 4 to
reduce the total number of lock/unlock cycles.
Link: http://lkml.kernel.org/r/1483647425-4135-4-git-send-email-longman@redhat.com
Signed-off-by: Waiman Long <longman@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "Du Changbin" <changbin.du@intel.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Jan Stancek <jstancek@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'drivers/usb/usbip/usbip_common.c')
0 files changed, 0 insertions, 0 deletions