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List:       kvm
Subject:    [RFC PATCH V3 0/5] Hi:
From:       Jason Wang <jasowang () redhat ! com>
Date:       2018-12-29 12:46:51
Message-ID: 20181229124656.3900-1-jasowang () redhat ! com
[Download RAW message or body]

This series tries to access virtqueue metadata through kernel virtual
address instead of copy_user() friends since they had too much
overheads like checks, spec barriers or even hardware feature
toggling.

Test shows about 24% improvement on TX PPS. It should benefit other
cases as well.

Changes from V2:
- fix buggy range overlapping check
- tear down MMU notifier during vhost ioctl to make sure invalidation
  request can read metadata userspace address and vq size without
  holding vq mutex.
Changes from V1:
- instead of pinning pages, use MMU notifier to invalidate vmaps and
  remap duing metadata prefetch
- fix build warning on MIPS

Jason Wang (5):
  vhost: generalize adding used elem
  vhost: fine grain userspace memory accessors
  vhost: rename vq_iotlb_prefetch() to vq_meta_prefetch()
  vhost: introduce helpers to get the size of metadata area
  vhost: access vq metadata through kernel virtual address

 drivers/vhost/net.c   |   4 +-
 drivers/vhost/vhost.c | 416 +++++++++++++++++++++++++++++++++++++-----
 drivers/vhost/vhost.h |  15 +-
 3 files changed, 384 insertions(+), 51 deletions(-)

-- 
2.17.1

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