[PATCH 0/5] block: Improve writethrough performance

[Kevin Wolf <kwolf@redhat.com>]

Write requests in writethrough mode mean that QEMU sends a separate
flush request (i.e. fdatasync) after each completed write request.
This is unnecessary overhead when we can just pass a flag for the write
request that gives us the desired FUA semantics.

Unfortunately, this made a problem in the adaptive polling algorithm
apparent that would result in a performance regression in some cases
with FUA support in file-posix. Therefore, adaptive polling is changed
in this series, too, to avoid the regression.

Kevin Wolf (5):
  file-posix: Support FUA writes
  block/io: Ignore FUA with cache.no-flush=on
  aio: Create AioPolledEvent
  aio-posix: Factor out adjust_polling_time()
  aio-posix: Separate AioPolledEvent per AioHandler

 include/block/aio.h     |  5 ++-
 include/block/raw-aio.h |  8 +++-
 util/aio-posix.h        |  1 +
 block/file-posix.c      | 26 ++++++++----
 block/io.c              |  4 ++
 block/io_uring.c        | 13 +++---
 block/linux-aio.c       | 24 +++++++++--
 util/aio-posix.c        | 94 ++++++++++++++++++++++++++---------------
 util/async.c            |  1 -
 meson.build             |  4 ++
 10 files changed, 125 insertions(+), 55 deletions(-)

-- 
2.48.1