[Xen-devel] [PATCH v2 0/4] xen/rcu: let rcu work better with core scheduling

[Juergen Gross <jgross@xxxxxxxx>]

Today the RCU handling in Xen is affecting scheduling in several ways.
It is raising sched softirqs without any real need and it requires
tasklets for rcu_barrier(), which interacts badly with core scheduling.

This small series repairs those issues.

Additionally some ASSERT()s are added for verification of sane rcu
handling. In order to avoid those triggering right away the obvious
violations are fixed.

Changes in V2:
- use get_cpu_maps() in rcu_barrier() handling
- avoid recursion in rcu_barrier() handling
- new patches 3 and 4

Juergen Gross (4):
  xen/rcu: use rcu softirq for forcing quiescent state
  xen/rcu: don't use stop_machine_run() for rcu_barrier()
  xen: add process_pending_softirqs_norcu() for keyhandlers
  xen/rcu: add assertions to debug build

 xen/arch/x86/mm/p2m-ept.c                   |  2 +-
 xen/arch/x86/numa.c                         |  4 +-
 xen/common/keyhandler.c                     |  6 +-
 xen/common/multicall.c                      |  1 +
 xen/common/rcupdate.c                       | 96 +++++++++++++++++++++--------
 xen/common/softirq.c                        | 19 ++++--
 xen/common/wait.c                           |  1 +
 xen/drivers/passthrough/amd/pci_amd_iommu.c |  2 +-
 xen/drivers/passthrough/vtd/iommu.c         |  2 +-
 xen/drivers/vpci/msi.c                      |  4 +-
 xen/include/xen/rcupdate.h                  | 23 +++++--
 xen/include/xen/softirq.h                   |  2 +
 12 files changed, 118 insertions(+), 44 deletions(-)

-- 
2.16.4


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