[PATCH v5 0/9] implement vcpu preempted check

Pan Xinhui
Thu, 20 Oct 2016 21:27:45 -0000

change from v4:
	spilt x86 kvm vcpu preempted check into two patches.
	add documentation patch.
	add x86 vcpu preempted check patch under xen
	add s390 vcpu preempted check patch
change from v3:
	add x86 vcpu preempted check patch
change from v2:
	no code change, fix typos, update some comments
change from v1:
	a simplier definition of default vcpu_is_preempted
	skip mahcine type check on ppc, and add config. remove dedicated macro.
	add one patch to drop overload of rwsem_spin_on_owner and mutex_spin_on_owner.
	add more comments
	thanks boqun and Peter's suggestion.

This patch set aims to fix lock holder preemption issues.

test-case:
perf record -a perf bench sched messaging -g 400 -p && perf report

18.09%  sched-messaging  [kernel.vmlinux]  [k] osq_lock
12.28%  sched-messaging  [kernel.vmlinux]  [k] rwsem_spin_on_owner
 5.27%  sched-messaging  [kernel.vmlinux]  [k] mutex_unlock
 3.89%  sched-messaging  [kernel.vmlinux]  [k] wait_consider_task
 3.64%  sched-messaging  [kernel.vmlinux]  [k] _raw_write_lock_irq
 3.41%  sched-messaging  [kernel.vmlinux]  [k] mutex_spin_on_owner.is
 2.49%  sched-messaging  [kernel.vmlinux]  [k] system_call

We introduce interface bool vcpu_is_preempted(int cpu) and use it in some spin
loops of osq_lock, rwsem_spin_on_owner and mutex_spin_on_owner.
These spin_on_onwer variant also cause rcu stall before we apply this patch set

We also have observed some performace improvements in uninx benchmark tests.

PPC test result:
1 copy - 0.94%
2 copy - 7.17%
4 copy - 11.9%
8 copy -  3.04%
16 copy - 15.11%

details below:
Without patch:

1 copy - File Write 4096 bufsize 8000 maxblocks      2188223.0 KBps  (30.0 s, 1
samples)
2 copy - File Write 4096 bufsize 8000 maxblocks      1804433.0 KBps  (30.0 s, 1
samples)
4 copy - File Write 4096 bufsize 8000 maxblocks      1237257.0 KBps  (30.0 s, 1
samples)
8 copy - File Write 4096 bufsize 8000 maxblocks      1032658.0 KBps  (30.0 s, 1
samples)
16 copy - File Write 4096 bufsize 8000 maxblocks       768000.0 KBps  (30.1 s, 1
samples)

With patch:

1 copy - File Write 4096 bufsize 8000 maxblocks      2209189.0 KBps  (30.0 s, 1
samples)
2 copy - File Write 4096 bufsize 8000 maxblocks      1943816.0 KBps  (30.0 s, 1
samples)
4 copy - File Write 4096 bufsize 8000 maxblocks      1405591.0 KBps  (30.0 s, 1
samples)
8 copy - File Write 4096 bufsize 8000 maxblocks      1065080.0 KBps  (30.0 s, 1
samples)
16 copy - File Write 4096 bufsize 8000 maxblocks       904762.0 KBps  (30.0 s, 1
samples)

X86 test result:
	test-case			after-patch	  before-patch
Execl Throughput                       |    18307.9 lps  |    11701.6 lps
File Copy 1024 bufsize 2000 maxblocks  |  1352407.3 KBps |   790418.9 KBps
File Copy 256 bufsize 500 maxblocks    |   367555.6 KBps |   222867.7 KBps
File Copy 4096 bufsize 8000 maxblocks  |  3675649.7 KBps |  1780614.4 KBps
Pipe Throughput                        | 11872208.7 lps  | 11855628.9 lps
Pipe-based Context Switching           |  1495126.5 lps  |  1490533.9 lps
Process Creation                       |    29881.2 lps  |    28572.8 lps
Shell Scripts (1 concurrent)           |    23224.3 lpm  |    22607.4 lpm
Shell Scripts (8 concurrent)           |     3531.4 lpm  |     3211.9 lpm
System Call Overhead                   | 10385653.0 lps  | 10419979.0 lps

Christian Borntraeger (1):
  s390/spinlock: Provide vcpu_is_preempted

Juergen Gross (1):
  x86, xen: support vcpu preempted check

Pan Xinhui (7):
  kernel/sched: introduce vcpu preempted check interface
  locking/osq: Drop the overload of osq_lock()
  kernel/locking: Drop the overload of {mutex,rwsem}_spin_on_owner
  powerpc/spinlock: support vcpu preempted check
  x86, paravirt: Add interface to support kvm/xen vcpu preempted check
  x86, kvm: support vcpu preempted check
  Documentation: virtual: kvm: Support vcpu preempted check

 Documentation/virtual/kvm/msr.txt     |  8 +++++++-
 arch/powerpc/include/asm/spinlock.h   |  8 ++++++++
 arch/s390/include/asm/spinlock.h      |  8 ++++++++
 arch/s390/kernel/smp.c                |  9 +++++++--
 arch/s390/lib/spinlock.c              | 25 ++++++++-----------------
 arch/x86/include/asm/paravirt_types.h |  2 ++
 arch/x86/include/asm/spinlock.h       |  8 ++++++++
 arch/x86/include/uapi/asm/kvm_para.h  |  3 ++-
 arch/x86/kernel/kvm.c                 | 12 ++++++++++++
 arch/x86/kernel/paravirt-spinlocks.c  |  6 ++++++
 arch/x86/kvm/x86.c                    | 18 ++++++++++++++++++
 arch/x86/xen/spinlock.c               |  3 ++-
 include/linux/sched.h                 | 12 ++++++++++++
 kernel/locking/mutex.c                | 15 +++++++++++++--
 kernel/locking/osq_lock.c             | 10 +++++++++-
 kernel/locking/rwsem-xadd.c           | 16 +++++++++++++---
 16 files changed, 135 insertions(+), 28 deletions(-)

--
2.4.11