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ros2 / rmw_fastrtps

Implementation of the ROS Middleware (rmw) Interface using eProsima's Fast RTPS.
Apache License 2.0
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CPU usage increase in v2.6.0 comparing with v2.2.0 #618

Closed Barry-Xu-2018 closed 2 years ago

Barry-Xu-2018 commented 2 years ago

Hardware platform is i.MX 6.
Test program is the same and the used version of fastdds is v2.6.0 and v2.2.0

One subscriber is on this hardware device. There are other 5 devices which will be started and send message to this device.
At subscriber side, there are about 500 messages received immediately after matching.
During this period,
v2.2.0: CPU usage (30% ~ 70%) will last for about 1 minute.
v2.6.0: CPU usage (28% ~ 72%) will last for about 3 minutes.

While receiving messages from one device,
v2.2.0: CPU usage is about 2.5%.
v2.6.0: CPU usage is about 7.5%.

For v2.6.1
If receive 100 messages, CPU usage is about 20%.
If receive 500 messages, CPU usage is about 50%. If receive 1000 messages, CPU usage is about 100%.

After analysis, the function using much CPU is

https://github.com/eProsima/Fast-DDS/blob/master/src/cpp/fastdds/subscriber/DataReaderImpl.cpp#L659

And

https://github.com/eProsima/Fast-DDS/blob/master/src/cpp/fastdds/subscriber/DataReaderImpl.cpp#L673 (It also calls above lookup_instance).

Above information isn't enough. I will continue to supplement information.

I am modifying DDS sample code to reproduce it and attach code.

fujitatomoya commented 2 years ago

This seems to be a digression for performance aspect. this directly affects number of sender devices we can connect or support to the receiver as requirement of business logic.

MiguelCompany commented 2 years ago

@Barry-Xu-2018 @fujitatomoya I think this can be closed in favor of eProsima/Fast-DDS#2779, since I think it will only affect topics with keys, which are not used in ROS 2.

Barry-Xu-2018 commented 2 years ago

@MiguelCompany

@Barry-Xu-2018 @fujitatomoya I think this can be closed in favor of eProsima/Fast-DDS#2779, since I think it will only affect topics with keys, which are not used in ROS 2.

Yes. I am wrong to create issue here and forgot to close after creating https://github.com/eProsima/Fast-DDS/issues/2779.