Messages in this thread | | | Date | Wed, 15 Feb 2023 13:43:28 -0800 | Subject | Re: [PATCH] x86/resctrl: Only show tasks' pids in current pid namespace | From | Reinette Chatre <> |
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Hi Shawn,
On 1/15/2023 11:12 PM, Shawn Wang wrote: > When writing a task id to the "tasks" file in an rdtgroup, > rdtgroup_tasks_write() treats the pid as a number in the current pid > namespace. But when reading the "tasks" file, rdtgroup_tasks_show() shows > the list of global pids from the init namespace. If current pid namespace > is not the init namespace, pids in "tasks" will be confusing and incorrect. > > To be more robust, let the "tasks" file only show pids in the current pid > namespace. >
Is it possible to elaborate more on the use case that this is aiming to address? It is unexpected to me that resource management is approached from within a container. My expectation is that the resource management and monitoring is done from the host.
> Signed-off-by: Shawn Wang <shawnwang@linux.alibaba.com> > --- > arch/x86/kernel/cpu/resctrl/rdtgroup.c | 8 ++++++-- > 1 file changed, 6 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c > index 5993da21d822..9e97ae24c159 100644 > --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c > +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c > @@ -718,11 +718,15 @@ static ssize_t rdtgroup_tasks_write(struct kernfs_open_file *of, > static void show_rdt_tasks(struct rdtgroup *r, struct seq_file *s) > { > struct task_struct *p, *t; > + pid_t pid; > > rcu_read_lock(); > for_each_process_thread(p, t) { > - if (is_closid_match(t, r) || is_rmid_match(t, r)) > - seq_printf(s, "%d\n", t->pid); > + if (is_closid_match(t, r) || is_rmid_match(t, r)) { > + pid = task_pid_vnr(t); > + if (pid) > + seq_printf(s, "%d\n", pid); > + } > } > rcu_read_unlock(); > }
This looks like it would solve the stated problem. Does it slow down reading a tasks file in a measurable way?
Reinette
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