Ubuntu-sponsors: In additional the the PPA, the debdiff is also attached here.
** Description changed: - Pipewire tries to acquire a realtime priority when it starts via the - libpipewire-module-rt plugin. By default, it prefers to use the - org.freedesktop.portal.Realtime interface if xdg-desktop-portal is - running (it checks if org.freedesktop.portal.Desktop exists on the - session bus). If xdg-desktop-portal isn't running, it uses rtkit - directly - see - https://gitlab.freedesktop.org/pipewire/pipewire/-/tree/1.2.7/src/modules?ref_type=tags#L932. + [Impact] + Restarting the pipewire user daemon causes it to lose realtime privileges, potentially resulting in hard-to-diagnose choppy audio. + + [Test plan] + 1. Fresh boot machine + 2. See expected realtime parameters + ps -e -o pri,ni,comm | grep wire + 30 -11 pipewire + 19 0 pipewire + 30 -11 wireplumber + 30 -11 pipewire-pulse + 3. Restart the services + systemctl --user restart pipewire wireplumber pipewire-pulse + 4. Ensure the realtime parameters are unchanged from before the restart, + ps -e -o pri,ni,comm | grep wire + 30 -11 pipewire + 19 0 pipewire + 30 -11 wireplumber + 30 -11 pipewire-pulse + + [Regression potential] + Backporting both commit dd08d451e3019f4ec6285ecb14d4c746b6e1d420 and 522236e41043a558a825da4cee70ee31ce607147 has a very low regression potential. The first change is purely refactoring commit, which enhances code clarity by renaming functions and variables to better differentiate between pidfds and /proc/$PID directory file descriptors without altering any underlying logic or behavior. The second fixes a specific bug where a function was incorrectly called with a pidfd instead of a /proc/$PID directory file descriptor, introducing a new, correct pidfd-aware function. The PIDFD_GET_PID_NAMESPACE ioctl is a standard Linux kernel interface for interacting with PID file descriptors. Its usage here is straightforward and unlikely to cause unexpected side effects if the underlying kernel support is present. + + [Original report] + Pipewire tries to acquire a realtime priority when it starts via the libpipewire-module-rt plugin. By default, it prefers to use the org.freedesktop.portal.Realtime interface if xdg-desktop-portal is running (it checks if org.freedesktop.portal.Desktop exists on the session bus). If xdg-desktop-portal isn't running, it uses rtkit directly - see https://gitlab.freedesktop.org/pipewire/pipewire/-/tree/1.2.7/src/modules?ref_type=tags#L932. I started looking at this because I have an annoying issue with my audio which results in my speakers making popping noises frequently when they're outputting anything. I have another issue where my USB speakers are frequently not detected by pipewire without restarting it. When pipewire starts with a new session, it acquires a realtime priority by using rtkit directly because xdg-desktop-portal isn't running at this stage. However, if you restart pipewire manually later on when xdg- desktop-portal is running, pipewire uses the portal interface to request a realtime priority, and this fails with xdg-desktop-portal outputting the following error to the journal: Apr 13 02:58:01 farnsworth xdg-desktop-por[7283]: Realtime error: Could not get pidns: Could not fstatat ns/pid: Not a directory The libpipewire-module-rt plugin does have an option to disable usage of the portal interface for requesting a realtime priority (rtportal.enabled=false). This is tested with pipewire 1.2.7 in plucky. ** Description changed: [Impact] Restarting the pipewire user daemon causes it to lose realtime privileges, potentially resulting in hard-to-diagnose choppy audio. [Test plan] 1. Fresh boot machine 2. See expected realtime parameters ps -e -o pri,ni,comm | grep wire - 30 -11 pipewire - 19 0 pipewire - 30 -11 wireplumber - 30 -11 pipewire-pulse + 30 -11 pipewire + 19 0 pipewire + 30 -11 wireplumber + 30 -11 pipewire-pulse 3. Restart the services - systemctl --user restart pipewire wireplumber pipewire-pulse + systemctl --user restart pipewire wireplumber pipewire-pulse 4. Ensure the realtime parameters are unchanged from before the restart, ps -e -o pri,ni,comm | grep wire - 30 -11 pipewire - 19 0 pipewire - 30 -11 wireplumber - 30 -11 pipewire-pulse + 30 -11 pipewire + 19 0 pipewire + 30 -11 wireplumber + 30 -11 pipewire-pulse [Regression potential] Backporting both commit dd08d451e3019f4ec6285ecb14d4c746b6e1d420 and 522236e41043a558a825da4cee70ee31ce607147 has a very low regression potential. The first change is purely refactoring commit, which enhances code clarity by renaming functions and variables to better differentiate between pidfds and /proc/$PID directory file descriptors without altering any underlying logic or behavior. The second fixes a specific bug where a function was incorrectly called with a pidfd instead of a /proc/$PID directory file descriptor, introducing a new, correct pidfd-aware function. The PIDFD_GET_PID_NAMESPACE ioctl is a standard Linux kernel interface for interacting with PID file descriptors. Its usage here is straightforward and unlikely to cause unexpected side effects if the underlying kernel support is present. [Original report] Pipewire tries to acquire a realtime priority when it starts via the libpipewire-module-rt plugin. By default, it prefers to use the org.freedesktop.portal.Realtime interface if xdg-desktop-portal is running (it checks if org.freedesktop.portal.Desktop exists on the session bus). If xdg-desktop-portal isn't running, it uses rtkit directly - see https://gitlab.freedesktop.org/pipewire/pipewire/-/tree/1.2.7/src/modules?ref_type=tags#L932. I started looking at this because I have an annoying issue with my audio which results in my speakers making popping noises frequently when they're outputting anything. I have another issue where my USB speakers are frequently not detected by pipewire without restarting it. When pipewire starts with a new session, it acquires a realtime priority by using rtkit directly because xdg-desktop-portal isn't running at this stage. However, if you restart pipewire manually later on when xdg- desktop-portal is running, pipewire uses the portal interface to request a realtime priority, and this fails with xdg-desktop-portal outputting the following error to the journal: Apr 13 02:58:01 farnsworth xdg-desktop-por[7283]: Realtime error: Could not get pidns: Could not fstatat ns/pid: Not a directory The libpipewire-module-rt plugin does have an option to disable usage of the portal interface for requesting a realtime priority (rtportal.enabled=false). This is tested with pipewire 1.2.7 in plucky. + + [Additional information] + See the xdg-desktop-portal package rebuild here: + https://launchpad.net/~charles05/+archive/ubuntu/ppa/+packages ** Patch added: "xdg-desktop-portal_1.20.0+ds-2ubuntu1_1.20.0+ds-2ubuntu2.diff" https://bugs.launchpad.net/ubuntu/+source/pipewire/+bug/2107340/+attachment/5891838/+files/xdg-desktop-portal_1.20.0+ds-2ubuntu1_1.20.0+ds-2ubuntu2.diff ** Tags added: desktop-needs-sru -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/2107340 Title: [SRU] Pipewire fails to reacquire a realtime priority when restarted To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/pipewire/+bug/2107340/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
