[Xen-devel] [PATCH v5 0/2] Refactor ioreq server for better performance.

[Yu Zhang <yu.c.zhang@xxxxxxxxxxxxxxx>]

XenGT leverages ioreq server to track and forward the accesses to
GPU I/O resources, e.g. the PPGTT(per-process graphic translation
tables). Currently, ioreq server uses rangeset to track the BDF/
PIO/MMIO ranges to be emulated. To select an ioreq server, the 
rangeset is searched to see if the I/O range is recorded. However,
traversing the link list inside rangeset could be time consuming
when number of ranges is too high. On HSW platform, number of PPGTTs
for each vGPU could be several hundred. On BDW, this value could
be several thousand.  This patch series refactored rangeset to base
it on red-back tree, so that the searching would be more efficient. 

Besides, this patchset also splits the tracking of MMIO and guest
ram ranges into different rangesets. And to accommodate more ranges,
limitation of the number of ranges in an ioreq server, MAX_NR_IO_RANGES
is changed - future patches might be provided to tune this with other
approaches.


Changes in v5: 
1> Use gpfn, instead of gpa to track guest write-protected pages;
2> Remove redundant conditional statement in routine find_range().

Changes in v4: 
Keep the name HVMOP_IO_RANGE_MEMORY for MMIO resources, and add 
a new one, HVMOP_IO_RANGE_WP_MEM, for write-protected memory.

Changes in v3: 
1> Use a seperate rangeset for guest ram pages in ioreq server;
2> Refactor rangeset, instead of introduce a new data structure.

Changes in v2: 
1> Split the original patch into 2;
2> Take Paul Durrant's comments:
  a> Add a name member in the struct rb_rangeset, and use the 'q' 
debug key to dump the ranges in ioreq server;
  b> Keep original routine names for hvm ioreq server;
  c> Commit message changes - mention that a future patch to change
the maximum ranges inside ioreq server.

Yu Zhang (2):
  Differentiate IO/mem resources tracked by ioreq server
  Refactor rangeset structure for better performance.

 tools/libxc/include/xenctrl.h    | 31 +++++++++++++++
 tools/libxc/xc_domain.c          | 55 +++++++++++++++++++++++++++
 xen/arch/x86/hvm/hvm.c           | 25 +++++++++++-
 xen/common/rangeset.c            | 82 +++++++++++++++++++++++++++++-----------
 xen/include/asm-x86/hvm/domain.h |  4 +-
 xen/include/public/hvm/hvm_op.h  |  1 +
 xen/include/public/hvm/ioreq.h   |  1 +
 7 files changed, 174 insertions(+), 25 deletions(-)

-- 
1.9.1


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