Re: [PATCH v4 1/7] x86/resctrl: Add multiple tasks to the resctrl group at once

Ilpo Järvinen
2023-04-19T12:58:47Z

On Mon, 17 Apr 2023, Babu Moger wrote:

> The resctrl task assignment for MONITOR or CONTROL group needs to be
> done one at a time. For example:
>
> $mount -t resctrl resctrl /sys/fs/resctrl/
> $mkdir /sys/fs/resctrl/clos1
> $echo 123 > /sys/fs/resctrl/clos1/tasks
> $echo 456 > /sys/fs/resctrl/clos1/tasks
> $echo 789 > /sys/fs/resctrl/clos1/tasks
>
> This is not user-friendly when dealing with hundreds of tasks.
>
> It can be improved by supporting the multiple task id assignment in
> one command with the tasks separated by commas. For example:
>
> $echo 123,456,789 > /sys/fs/resctrl/clos1/tasks
>
> Signed-off-by: Babu Moger <babu.moger@amd.com>
> ---
> Documentation/x86/resctrl.rst | 9 ++++++++-
> arch/x86/kernel/cpu/resctrl/rdtgroup.c | 31 ++++++++++++++++++++++++++++++-
> 2 files changed, 38 insertions(+), 2 deletions(-)
>
> diff --git a/Documentation/x86/resctrl.rst b/Documentation/x86/resctrl.rst
> index 387ccbcb558f..f28ed1443a6a 100644
> --- a/Documentation/x86/resctrl.rst
> +++ b/Documentation/x86/resctrl.rst
> @@ -292,7 +292,14 @@ All groups contain the following files:
> "tasks":
> Reading this file shows the list of all tasks that belong to
> this group. Writing a task id to the file will add a task to the
> - group. If the group is a CTRL_MON group the task is removed from
> + group. Multiple tasks can be added by separating the task ids
> + with commas. Tasks will be assigned sequentially in the order it
> + is entered.

"Tasks ... it is ..." doesn't sound correct.

> Failures while assigning the tasks will be aborted
> + immediately and tasks next in the sequence will not be assigned.
> + Users may need to retry them again. Failure details possibly with
> + pid will be logged in /sys/fs/resctrl/info/last_cmd_status file.
> +
> + If the group is a CTRL_MON group the task is removed from
> whichever previous CTRL_MON group owned the task and also from
> any MON group that owned the task. If the group is a MON group,
> then the task must already belong to the CTRL_MON parent of this
> diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> index 6ad33f355861..df5bd13440b0 100644
> --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> @@ -696,18 +696,41 @@ static ssize_t rdtgroup_tasks_write(struct kernfs_open_file *of,
> char *buf, size_t nbytes, loff_t off)
> {
> struct rdtgroup *rdtgrp;
> + char *pid_str;
> int ret = 0;
> pid_t pid;
>
> - if (kstrtoint(strstrip(buf), 0, &pid) || pid < 0)
> + if (nbytes == 0)
> return -EINVAL;
> +
> + buf[nbytes - 1] = '\0';
> +
> rdtgrp = rdtgroup_kn_lock_live(of->kn);
> if (!rdtgrp) {
> rdtgroup_kn_unlock(of->kn);
> return -ENOENT;
> }
> +
> +next:
> + if (!buf || buf[0] == '\0')
> + goto unlock;
> +
> rdt_last_cmd_clear();
>
> + pid_str = strim(strsep(&buf, ","));
> +
> + if (kstrtoint(pid_str, 0, &pid)) {
> + rdt_last_cmd_printf("Task list parsing error\n");
> + ret = -EINVAL;
> + goto unlock;
> + }
> +
> + if (pid < 0) {
> + rdt_last_cmd_printf("Invalid pid %d value\n", pid);
> + ret = -EINVAL;
> + goto unlock;
> + }
> +
> if (rdtgrp->mode == RDT_MODE_PSEUDO_LOCKED ||
> rdtgrp->mode == RDT_MODE_PSEUDO_LOCKSETUP) {
> ret = -EINVAL;
> @@ -716,6 +739,12 @@ static ssize_t rdtgroup_tasks_write(struct kernfs_open_file *of,
> }
>
> ret = rdtgroup_move_task(pid, rdtgrp, of);
> + if (ret) {
> + rdt_last_cmd_printf("Error while processing task %d\n", pid);
> + goto unlock;
> + } else {
> + goto next;
> + }

Why is this not changed into a while () loop??

>
> unlock:
> rdtgroup_kn_unlock(of->kn);
>
>

--
i.