liburing #1218

jmillan · 2023-11-14T15:43:00Z

Enable liburing usage for linux (kernel versions >= 6).

Use liburing to relay incoming RTP to Consumers. This greately reduces the number of system calls as just a single system call is needed to relay the incoming RTP packet to "every" Consumer, opposite to libuv which requires a system call to relay the RTP packet to "each" Consumer.

For efficiency, memory buffers are preallocated holding the data payload being sent.

Building mediasoup in a Linux machine with kernel >= 6 will enable the feature.
Running mediasoup in a Linux machine with kernel >= 6 will make use of the feature, if it was also enabled in build time.

NOTE: The numbers are really positive. Not only the CPU usage is reduced but it's also more stable.

Enable liburing usage for linux (kernel versions >= 6). Use liburing to relay incoming RTP to Consumers. This greately reduces the number of system calls as just a single system call is needed to relay the incoming RTP packet to "every" Consumer, opposite to libuv which requires a system call to relay the RTP packet to "each" Consumer. For efficiency, memory buffers are preallocated holding the data payload being sent.

nazar-pc · 2023-11-14T15:45:26Z

Okay, I'm glad you've tested it with positive outcome!
From my experience it is not always faster.

ibc · 2023-11-14T15:46:07Z

but it's also more stable

What does this mean exactly?

CHANGELOG.md

jmillan · 2023-11-14T15:47:12Z

Okay, I'm glad you've tested it with positive outcome!
From my experience it is not always faster.

In my tests you'll see the difference when larg-ish Routers, but not with small/normal ones. Testing with >200 consumers you'll see a noticeable difference.

nazar-pc · 2023-11-14T15:48:20Z

In my tests you'll see the difference when larg-ish Routers, but not with small/normal ones. Testing with >200 consumers you'll see a noticeable difference.

That makes a lot of sense and is to be expected. Squeezing more performance out of the same CPU core is always nice.

jmillan · 2023-11-14T15:53:29Z

The numbers are really positive. Not only the CPU usage is reduced but it's also more stable.

What does this mean exactly?

The CPU usage is more stable, it shows less spikes.

worker/src/DepLibUring.cpp

worker/src/handles/TcpConnectionHandle.cpp

worker/src/handles/UdpSocketHandle.cpp

worker/include/DepLibUring.hpp

worker/src/DepLibUring.cpp

The binary could have been prebuilt in a linux machine with kernel version >= 6, but then such image could be run on an older kernel. We need to check the kernel version in runtime and only enable the feature when appropriate.

worker/src/handles/UdpSocketHandle.cpp

worker/src/handles/TcpConnectionHandle.cpp

worker/src/handles/UdpSocketHandle.cpp

ibc

Love it now. Is it ready? Are you gonna add those entries we discussed into the dump data? Or in another PR?

jmillan · 2023-11-21T09:42:07Z

Love it now. Is it ready? Are you gonna add those entries we discussed into the dump data? Or in another PR?

Thanks, I'll do few changes in this PR and add those dump data too. I'll notify you once done.

RTP packets are retransmitted in batch, determined by the NACK RTCP packet. Make use of a single system call to send all Nacked packets.

Take advantage of a single system call when sending multiple compound packets.

The macro MS_LIBURING_SUPPORTED indicates that liburing capabilities are contained in the binary. IsRuntimeSupported() indicates whether the runtime can make use of such capabilities.

jmillan · 2023-11-21T15:00:39Z

@ibc, the initial version of liburing is ready to merge. Can you please take a look at today's 4 commits?

Send Nack-ed RTP using liburing
Send RTCP compound packets using liburing
Rename IsSupported() method for IsRuntimeSupported()
LibUring::Dump()

worker/include/DepLibUring.hpp

worker/src/DepLibUring.cpp

ashinrot · 2023-12-05T12:53:16Z

This greately reduces the number of system calls as just a single system call is needed to relay the incoming RTP packet to "every" Consumer

Hello, I'm working on udp syscall tunning on my local server, and trying lots of linux feature. IOUring seems to be a good solution, but how about sendmmsg syscall, it seems to be able to reduce the syscall with less code?

jmillan · 2023-12-05T15:12:06Z

but how about sendmmsg syscall, it seems to be able to reduce the syscall with less code?

You don't send multiple RTP packets in a raw to the same socket in mediasoup, but the "same" RTP packet from a Producer, to multiple sockets.

sendmmsg is for sending multiple packets to the same socket.

This PR is about using liburing when it's more convenient than libuv.

jmillan added 2 commits November 14, 2023 16:37

Update CHANGELOG.md

b819171

jmillan requested review from ibc and nazar-pc November 14, 2023 15:43