<html> <head> <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"> <style type="text/css" style="display:none;"> P {margin-top:0;margin-bottom:0;} </style> </head> <body dir="ltr"> <div class="elementToProof" style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 10pt; color: rgb(0, 0, 0);"> Hi Michal,</div> <div class="elementToProof" style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 10pt; color: rgb(0, 0, 0);"> <br> </div> <div class="elementToProof" style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 10pt; color: rgb(0, 0, 0);"> Thank you for your reply. I can grasp the point.</div> <div class="elementToProof" style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 10pt; color: rgb(0, 0, 0);"> Please let me ask more questions if I think of any.</div> <div class="elementToProof" style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 10pt; color: rgb(0, 0, 0);"> Besides, I will fix the name of slice in the picture soon.</div> <div class="elementToProof" style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 10pt; color: rgb(0, 0, 0);"> <br> </div> <div class="elementToProof" style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 10pt; color: rgb(0, 0, 0);"> BR-Matthew</div> <div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);"> <br> </div> <hr style="display: inline-block; width: 98%;"> <div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);"> <b>From:</b> Michal Koutnı<br> <b>Sent:</b> Monday, June 30, 2025 1:45 PM<br> <b>To:</b> Matthew Chae<br> <b>Cc:</b> systemd-devel@lists.freedesktop.org; Christopher Wong; Fredrik Hugosson; Umut Tezduyar Lindskog<br> <b>Subject:</b> Re: [systemd-devel] Question about the systemd slice hierarchy </div> <div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);"> <br> </div> <div style="font-size: 11pt;">Hello.<br> <br> On Mon, Jun 30, 2025 at 07:45:53AM +0000, Matthew Chae <Matthew.Chae@axis.com> wrote:<br> > I have some questions about "Example 1. Enabling and disabling controllers" from the slice-related man page linked below.<br> > <a href="https://www.freedesktop.org/software/systemd/man/latest/systemd.resource-control.html#" target="_blank" id="OWA7a6769cf-8e08-4f03-7a48-cdbf844d51b0" class="OWAAutoLink" rel="noopener noreferrer" data-auth="NotApplicable"> https://www.freedesktop.org/software/systemd/man/latest/systemd.resource-control.html#</a><br> ><br> > First, under system.slice, there is a slice named b.slice. Is this possible?<br> <br> No, the name encodes the path in reality.<br> <br> > Shouldn't it be named system-b.slice instead?<br> <br> That would be indeed the proper name of the slice that is pictured<br> there. You can fix it here [1] :-)<br> <br> > Second, under user.slice, there's a user@1000.service, and under that,<br> > there are app.slice and session.slice.<br> <br> If you check user@.service definition, you find that it sets Delegate=<br> -- this means that the service as seen from PID1 perspective was<br> delegated the manipulation of its (service's) cgroup subtree.<br> <br> > Can a slice like app.slice exist under a service unit like user@1000.service?<br> <br> This app.slice is a slice unit of the _user_ instance of systemd. It's<br> full system path would be:<br> /user.slice/user-1000.slice/user@1000.service/app.slice<br> <br> (app.slice is a random internal subcgroup for PID1)<br> <br> > If that's possible, what would be a use case for this kind of structure?<br> <br> It's turtles all the way down. One use case is structuring of processes<br> by user's desktop environment, some more info is in [2].<br> <br> HTH,<br> Michal<br> <br> <br> [1] <a href="https://github.com/systemd/systemd/blob/main/man/systemd.resource-control.xml" target="_blank" id="OWA4732ce65-c599-829e-7dfd-313ffb58891c" class="OWAAutoLink" rel="noopener noreferrer" data-auth="NotApplicable"> https://github.com/systemd/systemd/blob/main/man/systemd.resource-control.xml</a><br> [2] <a href="https://systemd.io/DESKTOP_ENVIRONMENTS/" target="_blank" id="OWAd2c409f0-abd0-6f11-bc47-cf22b26d66db" class="OWAAutoLink" rel="noopener noreferrer" data-auth="NotApplicable"> https://systemd.io/DESKTOP_ENVIRONMENTS/</a><br> </div> </body> </html>