Re: Question about LTTng Context
Amir Najafi Zadeh via lttng-dev <[email protected]> Thu, 11 Dec 2025 11:21:35 -0500
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--00000000000096c3360645af8af8 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable I'll try that too. Thanks for mentioning it. Cheers, Amir On Thu, 11 Dec 2025, 11:14 Michael Jeanson, <[email protected]> wrote: > On 12/11/25 10:51, Amir Najafi Zadeh wrote: > > Michael, Kienan, Thank you both for your replies. As you mentioned the > > cgroup namespace, it isn=E2=80=99t very helpful in some cases. Containe= rs may > > share the same cgroup namespace, and the container runtime often avoids > > giving each container a private cgroup namespace for performance and > > security reasons. Because of this, the cgroup namespace can=E2=80=99t b= e used as > > a reliable or unique label for filtering trace logs. > > > > In my case, with container-d you can inspect a container, find its PID, > > and then check /proc/<pid>/ns/cgroup, but you=E2=80=99ll see that diffe= rent > > containers often have the same cgroup namespace ID (e.g., in the > > following logs you can see the calico-node and kube-proxy containers > > sharing a cgroup ns). > > If you want to track containers, the pid namespace is the one used by > most container runtimes but I don't know specifically for container-d. > > > > > ``` > > Name: calico-node CID: > > b5624afe31b005725f4ba53c7b6fe758f3c09fabf013085231ff8b97588f6ace PID: > > 2243 cgroup_ns_inode: 4026531835 > > Name: kube-proxy CID: > > 52f3c12def7a680f61a925ac92dd5ebd5eba6cad17d671efbfd1d40db7dff624 PID: > > 1851 cgroup_ns_inode: 4026531835 > > >> MATCH FOUND: shares ns with container: > > b5624afe31b005725f4ba53c7b6fe758f3c09fabf013085231ff8b97588f6ace > > (calico-node) > > ``` > > > > Thanks again for your answers. I hope this feature appears in a future > > patch. > > > > Best, > > Amir > > > > On Thu, Dec 11, 2025 at 9:57=E2=80=AFAM Michael Jeanson <mjeanson@effic= ios.com > > <mailto:[email protected]>> wrote: > > > > On 12/11/25 09:30, Kienan Stewart via lttng-dev wrote: > > > Hi Amir, > > > > > > On 12/10/25 9:40 PM, Amir Najafi Zadeh via lttng-dev wrote: > > >> Hello everyone, > > >> > > >> I hope you=E2=80=99re doing well. My name is Amir, and I=E2=80= =99m a PhD student > in > > >> the Computer Science department at Stony Brook University, New > York. > > >> > > >> I have a question about the LTTng context that I haven=E2=80=99= t been > > able to > > >> find an answer for in the docs or man pages. Does LTTng support > > adding > > >> the cgroup ID or cgroup path as a context field? I want to > > filter my > > >> trace results based on cgroups. > > >> > > > > > > I think you're looking for the `cgroup_ns` context which adds th= e > > inum > > > of the cgroup namespace as a context field. > > > > This will give you the ID of the cgroup namespace but we don't have > > contexts for cgroups themselves. It's probably something we would > like > > to have but there is no concrete plans on implementing this at the > > moment. > > > > > > > >> If this isn=E2=80=99t supported, are there any plans to add it = in future > > >> versions, such as 2.14? > > >> > > >> For reference, I=E2=80=99m currently using LTTng 2.13 on Ubuntu= 24.04 > with > > >> kernel 6.8.0-87-generic. > > >> > > >> Cheers, > > >> Amir > > >> -- > > >> *Amirhossein Najafizadeh* > > >> *PhD Student, Computer Science Department, Stony Brook > > University, N.Y. > > >> File systems and Storage Lab (FSL) > > > > --00000000000096c3360645af8af8 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable <div dir=3D"auto">I'll try that too. Thanks for mentioning it.<div dir= =3D"auto"><br></div><div dir=3D"auto">Cheers,</div><div dir=3D"auto">Amir</= div></div><br><div class=3D"gmail_quote gmail_quote_container"><div dir=3D"= ltr" class=3D"gmail_attr">On Thu, 11 Dec 2025, 11:14 Michael Jeanson, <<= a href=3D"mailto:[email protected]">[email protected]</a>> wrote= :<br></div><blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;bor= der-left:1px #ccc solid;padding-left:1ex">On 12/11/25 10:51, Amir Najafi Za= deh wrote:<br> > Michael, Kienan, Thank you both for your replies. As you mentioned the= <br> > cgroup namespace, it isn=E2=80=99t very helpful in some cases. Contain= ers may <br> > share the same cgroup namespace, and the container runtime often avoid= s <br> > giving each container a private cgroup namespace for performance and <= br> > security reasons. Because of this, the cgroup namespace can=E2=80=99t = be used as <br> > a reliable or unique label for filtering trace logs.<br> > <br> > In my case, with container-d you can inspect a container, find its PID= , <br> > and then check /proc/<pid>/ns/cgroup, but you=E2=80=99ll see tha= t different <br> > containers often have the same cgroup namespace ID (e.g., in the <br> > following logs you can see the calico-node and kube-proxy containers <= br> > sharing a cgroup ns).<br> <br> If you want to track containers, the pid namespace is the one used by <br> most container runtimes but I don't know specifically for container-d.<= br> <br> > <br> > ```<br> > Name: calico-node =C2=A0CID: <br> > b5624afe31b005725f4ba53c7b6fe758f3c09fabf013085231ff8b97588f6ace =C2= =A0PID: <br> > 2243 =C2=A0cgroup_ns_inode: 4026531835<br> > Name: kube-proxy =C2=A0CID: <br> > 52f3c12def7a680f61a925ac92dd5ebd5eba6cad17d671efbfd1d40db7dff624 =C2= =A0PID: <br> > 1851 =C2=A0cgroup_ns_inode: 4026531835<br> >=C2=A0 =C2=A0 >> MATCH FOUND: shares ns with container: <br> > b5624afe31b005725f4ba53c7b6fe758f3c09fabf013085231ff8b97588f6ace <br> > (calico-node)<br> > ```<br> > <br> > Thanks again for your answers. I hope this feature appears in a future= <br> > patch.<br> > <br> > Best,<br> > Amir<br> > <br> > On Thu, Dec 11, 2025 at 9:57=E2=80=AFAM Michael Jeanson <<a href=3D= "mailto:[email protected]" target=3D"_blank" rel=3D"noreferrer">mjeanso= [email protected]</a> <br> > <mailto:<a href=3D"mailto:[email protected]" target=3D"_blank" = rel=3D"noreferrer">[email protected]</a>>> wrote:<br> > <br> >=C2=A0 =C2=A0 =C2=A0On 12/11/25 09:30, Kienan Stewart via lttng-dev wro= te:<br> >=C2=A0 =C2=A0 =C2=A0 > Hi Amir,<br> >=C2=A0 =C2=A0 =C2=A0 ><br> >=C2=A0 =C2=A0 =C2=A0 > On 12/10/25 9:40 PM, Amir Najafi Zadeh via lt= tng-dev wrote:<br> >=C2=A0 =C2=A0 =C2=A0 >> Hello everyone,<br> >=C2=A0 =C2=A0 =C2=A0 >><br> >=C2=A0 =C2=A0 =C2=A0 >> I hope you=E2=80=99re doing well. My name= is Amir, and I=E2=80=99m a PhD student in<br> >=C2=A0 =C2=A0 =C2=A0 >> the Computer Science department at Stony = Brook University, New York.<br> >=C2=A0 =C2=A0 =C2=A0 >><br> >=C2=A0 =C2=A0 =C2=A0 >> I have a question about the LTTng context= that I haven=E2=80=99t been<br> >=C2=A0 =C2=A0 =C2=A0able to<br> >=C2=A0 =C2=A0 =C2=A0 >> find an answer for in the docs or man pag= es. Does LTTng support<br> >=C2=A0 =C2=A0 =C2=A0adding<br> >=C2=A0 =C2=A0 =C2=A0 >> the cgroup ID or cgroup path as a context= field? I want to<br> >=C2=A0 =C2=A0 =C2=A0filter my<br> >=C2=A0 =C2=A0 =C2=A0 >> trace results based on cgroups.<br> >=C2=A0 =C2=A0 =C2=A0 >><br> >=C2=A0 =C2=A0 =C2=A0 ><br> >=C2=A0 =C2=A0 =C2=A0 > I think you're looking for the `cgroup_ns= ` context which adds the<br> >=C2=A0 =C2=A0 =C2=A0inum<br> >=C2=A0 =C2=A0 =C2=A0 > of the cgroup namespace as a context field.<b= r> > <br> >=C2=A0 =C2=A0 =C2=A0This will give you the ID of the cgroup namespace b= ut we don't have<br> >=C2=A0 =C2=A0 =C2=A0contexts for cgroups themselves. It's probably = something we would like<br> >=C2=A0 =C2=A0 =C2=A0to have but there is no concrete plans on implement= ing this at the<br> >=C2=A0 =C2=A0 =C2=A0moment.<br> > <br> >=C2=A0 =C2=A0 =C2=A0 ><br> >=C2=A0 =C2=A0 =C2=A0 >> If this isn=E2=80=99t supported, are ther= e any plans to add it in future<br> >=C2=A0 =C2=A0 =C2=A0 >> versions, such as 2.14?<br> >=C2=A0 =C2=A0 =C2=A0 >><br> >=C2=A0 =C2=A0 =C2=A0 >> For reference, I=E2=80=99m currently usin= g LTTng 2.13 on Ubuntu 24.04 with<br> >=C2=A0 =C2=A0 =C2=A0 >> kernel 6.8.0-87-generic.<br> >=C2=A0 =C2=A0 =C2=A0 >><br> >=C2=A0 =C2=A0 =C2=A0 >> Cheers,<br> >=C2=A0 =C2=A0 =C2=A0 >> Amir<br> >=C2=A0 =C2=A0 =C2=A0 >> --<br> >=C2=A0 =C2=A0 =C2=A0 >> *Amirhossein Najafizadeh*<br> >=C2=A0 =C2=A0 =C2=A0 >> *PhD Student, Computer Science Department= , Stony Brook<br> >=C2=A0 =C2=A0 =C2=A0University, N.Y.<br> >=C2=A0 =C2=A0 =C2=A0 >> File systems and Storage Lab (FSL)<br> > <br> <br> </blockquote></div> --00000000000096c3360645af8af8--