Re: [PATCH v10 01/10] x86/resctrl: Add multiple tasks to the resctrl group at once

[Ilpo Järvinen]

On Fri, 15 Sep 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/ctrl_grp1
>   $echo 123 > /sys/fs/resctrl/ctrl_grp1/tasks
>   $echo 456 > /sys/fs/resctrl/ctrl_grp1/tasks
>   $echo 789 > /sys/fs/resctrl/ctrl_grp1/tasks
> 
> This is not user-friendly when dealing with hundreds of tasks.
> 
> Support multiple task assignment in one command with tasks ids separated
> by commas. For example:
>   $echo 123,456,789 > /sys/fs/resctrl/ctrl_grp1/tasks
> 
> Reviewed-by: Tan Shaopeng <tan.shaopeng@xxxxxxxxxxxxxx>
> Tested-by: Tan Shaopeng <tan.shaopeng@xxxxxxxxxxxxxx>
> Reviewed-by: Reinette Chatre <reinette.chatre@xxxxxxxxx>
> Reviewed-by: Fenghua Yu <fenghua.yu@xxxxxxxxx>
> Signed-off-by: Babu Moger <babu.moger@xxxxxxx>
> ---
>  Documentation/arch/x86/resctrl.rst     |  9 ++++++++-
>  arch/x86/kernel/cpu/resctrl/rdtgroup.c | 25 ++++++++++++++++++++++---
>  2 files changed, 30 insertions(+), 4 deletions(-)
> 
> diff --git a/Documentation/arch/x86/resctrl.rst b/Documentation/arch/x86/resctrl.rst
> index cb05d90111b4..8154e9975d1e 100644
> --- a/Documentation/arch/x86/resctrl.rst
> +++ b/Documentation/arch/x86/resctrl.rst
> @@ -299,7 +299,14 @@ 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. Multiple
> +	failures are not supported. A single failure encountered while
> +	attempting to assign a task will cause the operation to abort and
> +	already added tasks before the failure will remain in the group.
> +	Failures will be logged to /sys/fs/resctrl/info/last_cmd_status.
> +
> +	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 725344048f85..f0d163950969 100644
> --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> @@ -696,11 +696,10 @@ 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)
> -		return -EINVAL;
>  	rdtgrp = rdtgroup_kn_lock_live(of->kn);
>  	if (!rdtgrp) {
>  		rdtgroup_kn_unlock(of->kn);
> @@ -715,7 +714,27 @@ static ssize_t rdtgroup_tasks_write(struct kernfs_open_file *of,
>  		goto unlock;
>  	}
>  
> -	ret = rdtgroup_move_task(pid, rdtgrp, of);
> +	while (buf && buf[0] != '\0' && buf[0] != '\n') {
> +		pid_str = strim(strsep(&buf, ","));
> +
> +		if (kstrtoint(pid_str, 0, &pid)) {
> +			rdt_last_cmd_printf("Task list parsing error pid %s\n", pid_str);
> +			ret = -EINVAL;
> +			break;
> +		}
> +
> +		if (pid < 0) {
> +			rdt_last_cmd_printf("Invalid pid %d\n", pid);
> +			ret = -EINVAL;
> +			break;
> +		}
> +
> +		ret = rdtgroup_move_task(pid, rdtgrp, of);
> +		if (ret) {
> +			rdt_last_cmd_printf("Error while processing task %d\n", pid);
> +			break;
> +		}
> +	}
>  
>  unlock:
>  	rdtgroup_kn_unlock(of->kn);
> 

Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxxxxxx>

-- 
 i.