<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40"> <head> <meta http-equiv="Content-Type" content="text/html; charset=us-ascii"> <meta name="Generator" content="Microsoft Word 15 (filtered medium)"> <style></style> </head> <body lang="EN-US" link="#467886" vlink="#96607D" style="word-wrap:break-word"> <div class="WordSection1"> Hi systemd-devel,<o:p></o:p> <o:p> </o:p> When using the systemd-logind design for suspend, systemd services can receive the PrepareForSleep DBus signal from systemd-logind with the Boolean argument false to know when the system is exiting from suspend - <a href="https://systemd.io/INHIBITOR_LOCKS/">https://systemd.io/INHIBITOR_LOCKS/</a><o:p></o:p> <o:p> </o:p> We want to be able to measure the time between triggering a suspend exit (AKA resume), and the moment that the system can be considered “resumed”.<o:p></o:p> <ul style="margin-top:0in" type="disc"> <li class="MsoListParagraph" style="margin-left:0in;mso-list:l0 level1 lfo3">The definition of resumed would likely be that all systemd services registered with the PrepareForSleep DBus signal have completed their callbacks and re-acquired sleep delay inhibitor locks.<o:p></o:p></li></ul> <o:p> </o:p> Normally for measuring boot times after power-on, it is very easy to use timestamps of activation of Type=notify services and systemd targets, but when resuming from a low power state with systemd, I’m not sure what the easiest / best practices are. If I understand correctly, as part of systemd-logind’s suspend design, suspend.target is reached before systemd-logind broadcasts PrepareForSleep “false” signal, so suspend.target’s activation timestamp does not represent the time that systemd services have had the opportunity to re-acquire sleep delay inhibitor locks.<o:p></o:p> <o:p> </o:p> Some ideas…<o:p></o:p> <o:p> </o:p> Is there some way for a systemd target to be dependent on services reaching some custom state like “resumed”?<o:p></o:p> <o:p> </o:p> Another idea could be to have another systemd service, let’s say it is called “suspend-listener.service”, started at boot time to which systemd services that acquire sleep delay inhibitor locks would register with. Then after these registered services re-acquire sleep delay inhibitor locks, they notify suspend-listener that they are successfully resumed. Only once suspend-listener is notified that all registered services have resumed successfully, the system is considered “resumed”.<o:p></o:p> <o:p> </o:p> Or suspend-listener could have a predefined list of services that need to acquire inhibitor locks, and it itself can register with PrepareForSleep. When it receives PrepareForSleep “false”, suspend-listener could busy-poll ListInhibitors DBus method until all predefined services have successfully re-acquired sleep delay inhibitor locks.<o:p></o:p> <o:p> </o:p> Thank you,<o:p></o:p> Eric<o:p></o:p> </div> </body> </html>