[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Qemu-devel] [PATCH for-2.3 0/5] aio: Support epoll by introducing qemu_
From: |
Fam Zheng |
Subject: |
[Qemu-devel] [PATCH for-2.3 0/5] aio: Support epoll by introducing qemu_poll abstraction |
Date: |
Tue, 25 Nov 2014 16:07:54 +0800 |
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).
To show some data from my test on current master:
- As a base point (10~20 fd's), it takes 22000 ns for each qemu_poll_ns.
- Add 10 virtio-serial, which adds some 6 hundreds of fd's in the main loop.
The time spent in qemu_poll_ns goes up to 75000 ns.
This series introduces qemu_poll, which is implemented with g_poll and epoll,
decided at configure time with CONFIG_EPOLL.
After this change, the times to do the same thing with qemu_poll (more
precisely, with a sequence of qemu_poll_set_fds(), qemu_poll(),
qemu_poll_get_events() followed by syncing back to gpollfds), are reduced to
21000 ns and 25000 ns, respectively.
We are still not O(1) because as a transition, the qemu_poll_set_fds before
qemu_poll is not optimized out yet.
Fam
Fam Zheng (5):
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
Makefile.objs | 2 +
aio-posix.c | 52 ++++-----
async.c | 5 +-
include/block/aio.h | 7 +-
include/qemu/poll.h | 40 +++++++
include/qemu/timer.h | 13 ---
include/qemu/typedefs.h | 2 +
main-loop.c | 35 ++++++-
poll-glib.c | 130 +++++++++++++++++++++++
poll-linux.c | 216 ++++++++++++++++++++++++++++++++++++++
qemu-timer.c | 21 ----
tests/Makefile | 2 +
tests/test-poll.c | 272 ++++++++++++++++++++++++++++++++++++++++++++++++
13 files changed, 723 insertions(+), 74 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
- [Qemu-devel] [PATCH for-2.3 0/5] aio: Support epoll by introducing qemu_poll abstraction,
Fam Zheng <=
- [Qemu-devel] [PATCH for-2.3 1/5] poll: Introduce QEMU Poll API, Fam Zheng, 2014/11/25
- [Qemu-devel] [PATCH for-2.3 3/5] poll: Add epoll implementation for qemu_poll, Fam Zheng, 2014/11/25
- [Qemu-devel] [PATCH for-2.3 2/5] posix-aio: Use QEMU poll interface, Fam Zheng, 2014/11/25
- [Qemu-devel] [PATCH for-2.3 4/5] main-loop: Replace qemu_poll_ns with qemu_poll, Fam Zheng, 2014/11/25
- [Qemu-devel] [PATCH for-2.3 5/5] tests: Add test case for qemu_poll, Fam Zheng, 2014/11/25
- Re: [Qemu-devel] [PATCH for-2.3 0/5] aio: Support epoll by introducing qemu_poll abstraction, Stefan Hajnoczi, 2014/11/25