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

Moger, Babu
2023-04-19T14:52:26Z

Hi Jarvinen,

On 4/19/23 07:58, Ilpo Järvinen wrote:
> 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.

How about "Tasks will be assigned sequentially in the order they are entered."

>
>> 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??

Yes. I can change that. It might look bit more cleaner.

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

--
Thanks
Babu Moger