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[Qemu-devel] [PATCH v4 0/7] aio: Support epoll by introducing qemu_poll


From: Fam Zheng
Subject: [Qemu-devel] [PATCH v4 0/7] aio: Support epoll by introducing qemu_poll abstraction
Date: Wed, 29 Apr 2015 11:24:24 +0800

v4: Rebase to 2.3 and rerun tests.  timerfd+epoll shows clear improvement over
    current master when the virtio-console device attaches more fds to the main
    loop:

    syscall         high # of fd      low # of fd
    -------------------------------------------------
    qemu.git(ppoll) 24                83
    ppoll+epoll     49                82
    timerfd+epoll   49                91
    glib            20                82

    (In high # of fd case, 3 activated but idle virtio-console devices are
    attached, which will add us hundereds of fds to poll)

    Although a new epoll_pwait1 syscall is still being worked on [1], the QEMU
    part to make use of that (if any) will base on this, so let's merge it
    first.
    
    [1]: http://www.spinics.net/lists/linux-api/msg08216.html


v1 cover letter
---------------

ppoll(2) doesn't scale as well as epoll: The elapsed time of the syscall is
linear to the number of fd's we poll, which hurts performance a bit when the
number of devices are many, or when a virtio device registers many virtqueues
(virtio-serial, for instance).

This series introduces qemu_poll, which is implemented  with g_poll and epoll,
decided at configure time with CONFIG_EPOLL.

Fam


Fam Zheng (7):
  poll: Introduce QEMU Poll API
  posix-aio: Use QEMU poll interface
  poll: Add epoll implementation for qemu_poll
  main-loop: Replace qemu_poll_ns with qemu_poll
  tests: Add test case for qemu_poll
  poll-glib: Support ppoll
  poll-linux: Add timerfd support

 Makefile.objs           |   2 +
 aio-posix.c             |  26 +++-
 async.c                 |   3 +
 include/block/aio.h     |   6 +
 include/qemu/poll.h     |  40 +++++++
 include/qemu/timer.h    |  13 --
 include/qemu/typedefs.h |   4 +-
 main-loop.c             |  35 +++++-
 poll-glib.c             | 153 ++++++++++++++++++++++++
 poll-linux.c            | 310 ++++++++++++++++++++++++++++++++++++++++++++++++
 qemu-timer.c            |  28 -----
 tests/Makefile          |   2 +
 tests/test-poll.c       | 272 ++++++++++++++++++++++++++++++++++++++++++
 13 files changed, 841 insertions(+), 53 deletions(-)
 create mode 100644 include/qemu/poll.h
 create mode 100644 poll-glib.c
 create mode 100644 poll-linux.c
 create mode 100644 tests/test-poll.c

-- 
1.9.3




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