kvm tools: Add ioeventfd support
ioeventfd is way provided by KVM to receive notifications about
reads and writes to PIO and MMIO areas within the guest.
Such notifications are usefull if all we need to know is that
a specific area of the memory has been changed, and we don't need
a heavyweight exit to happen.
The implementation uses epoll to scale to large number of ioeventfds.
Benchmarks ran on a seperate (non boot) 1GB virtio-blk device, formatted
as ext4, using bonnie++.
cmd line:
# bonnie++ -d temp/ -c 2 -s 768 -u 0
Before:
Version 1.96 ------Sequential Output------ --Sequential Input- --Random-
Concurrency 2 -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks--
Machine Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP /sec %CP
tux 768M 498 99 381127 74 269712 48 2871 99 717109 50 +++++ +++
Latency 18368us 31063us 21281us 3017us 6875us 251ms
Version 1.96 ------Sequential Create------ --------Random Create--------
tux -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete--
files /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP
16 +++++ +++ +++++ +++ +++++ +++ +++++ +++ +++++ +++ +++++ +++
Latency 148us 588us 2792us 1547us 1543us 218us
After:
Version 1.96 ------Sequential Output------ --Sequential Input- --Random-
Concurrency 2 -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks--
Machine Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP /sec %CP
tux 768M 499 99 459779 73 350689 54 2997 99 860395 58 +++++ +++
Latency 17194us 14619us 26358us 4055us 7890us 44122us
Version 1.96 ------Sequential Create------ --------Random Create--------
tux -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete--
files /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP
16 +++++ +++ +++++ +++ +++++ +++ +++++ +++ +++++ +++ +++++ +++
Latency 135us 567us 2564us 134us 1500us 231us
Signed-off-by: Sasha Levin <levinsasha928@gmail.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
4 files changed
