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Date: Wed, 13 Nov 2019 19:23:07 +0100
From: Borislav Petkov <bp@...en8.de>
To: Chen Yu <yu.c.chen@...el.com>
Cc: x86@...nel.org, Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>,
"H. Peter Anvin" <hpa@...or.com>,
Reinette Chatre <reinette.chatre@...el.com>,
Fenghua Yu <fenghua.yu@...el.com>,
Tony Luck <tony.luck@...el.com>, linux-kernel@...r.kernel.org,
linux-fsdevel@...r.kernel.org,
Alexey Dobriyan <adobriyan@...il.com>,
Andrew Morton <akpm@...ux-foundation.org>,
Michal Hocko <mhocko@...e.com>,
Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [PATCH] x86/resctrl: Add task resctrl information display
On Thu, Nov 07, 2019 at 11:27:31AM +0800, Chen Yu wrote:
> Monitoring tools that want to find out which resctrl CTRL
> and MONITOR groups a task belongs to must currently read
> the "tasks" file in every group until they locate the process
> ID.
>
> Add an additional file /proc/{pid}/resctrl to provide this
> information.
>
> For example:
> cat /proc/1193/resctrl
> CTRL_MON:/ctrl_grp0
> MON:/ctrl_grp0/mon_groups/mon_grp0
>
> If the resctrl filesystem has not been mounted,
> reading /proc/{pid}/resctrl returns an error:
> cat: /proc/1193/resctrl: No such device
>
> Tested-by: Jinshi Chen <jinshi.chen@...el.com>
> Reviewed-by: Reinette Chatre <reinette.chatre@...el.com>
> Reviewed-by: Fenghua Yu <fenghua.yu@...el.com>
> Reviewed-by: Tony Luck <tony.luck@...el.com>
> Signed-off-by: Chen Yu <yu.c.chen@...el.com>
>
> ---
> arch/x86/include/asm/resctrl_sched.h | 4 +++
> arch/x86/kernel/cpu/resctrl/rdtgroup.c | 46 ++++++++++++++++++++++++++
> fs/proc/base.c | 9 +++++
^^^^^^^^^^^^^^^
So you're touching this file here and yet your Cc list doesn't have
*anyone* who might be responsible for the proc fs (yeah, you have
linux-fsdevel but I don't think that's enough). Have you heard of
scripts/get_maintainer.pl?
Use it in the future.
Cc-ing some more people for the generic /proc bits.
> 3 files changed, 59 insertions(+)
>
> diff --git a/arch/x86/include/asm/resctrl_sched.h b/arch/x86/include/asm/resctrl_sched.h
> index f6b7fe2833cc..bba362e0e00f 100644
> --- a/arch/x86/include/asm/resctrl_sched.h
> +++ b/arch/x86/include/asm/resctrl_sched.h
> @@ -5,6 +5,7 @@
> #ifdef CONFIG_X86_CPU_RESCTRL
>
> #include <linux/sched.h>
> +#include <linux/proc_fs.h>
> #include <linux/jump_label.h>
>
> #define IA32_PQR_ASSOC 0x0c8f
> @@ -84,6 +85,9 @@ static inline void resctrl_sched_in(void)
> __resctrl_sched_in();
> }
>
> +int proc_resctrl_show(struct seq_file *m, struct pid_namespace *ns,
> + struct pid *pid, struct task_struct *tsk);
> +
> #else
>
> static inline void resctrl_sched_in(void) {}
> diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> index a46dee8e78db..2317174174e9 100644
> --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> @@ -727,6 +727,52 @@ static int rdtgroup_tasks_show(struct kernfs_open_file *of,
> return ret;
> }
>
> +int proc_resctrl_show(struct seq_file *s, struct pid_namespace *ns,
> + struct pid *pid, struct task_struct *tsk)
> +{
> + struct rdtgroup *rdtg;
> + int ret = 0;
> +
> + mutex_lock(&rdtgroup_mutex);
> +
> + /* Make sure resctrl has been mounted. */
> + if (!static_branch_unlikely(&rdt_enable_key)) {
> + ret = -ENODEV;
> + goto unlock;
> + }
> +
> + list_for_each_entry(rdtg, &rdt_all_groups, rdtgroup_list) {
> + struct rdtgroup *crg;
> +
> + /*
> + * Task information is only relevant for shareable
> + * and exclusive groups.
> + */
> + if (rdtg->mode != RDT_MODE_SHAREABLE &&
> + rdtg->mode != RDT_MODE_EXCLUSIVE)
> + continue;
> +
> + if (rdtg->closid == tsk->closid) {
Save an indentation level:
if (rdtg->closid != tsk->closid)
continue;
seq_printf...
> + seq_printf(s, "CTRL_MON:/%s\n", rdtg->kn->name);
> + list_for_each_entry(crg, &rdtg->mon.crdtgrp_list,
> + mon.crdtgrp_list) {
> + if (tsk->rmid != crg->mon.rmid)
> + continue;
> + seq_printf(s, "MON:%s%s/mon_groups/%s\n",
> + rdtg == &rdtgroup_default ? "" : "/",
> + rdtg->kn->name, crg->kn->name);
> + goto unlock;
> + }
> + goto unlock;
> + }
> + }
> + ret = -ENOENT;
> +unlock:
> + mutex_unlock(&rdtgroup_mutex);
> +
> + return ret;
> +}
> +
> static int rdt_last_cmd_status_show(struct kernfs_open_file *of,
> struct seq_file *seq, void *v)
> {
> diff --git a/fs/proc/base.c b/fs/proc/base.c
> index ebea9501afb8..d8a61db78db5 100644
> --- a/fs/proc/base.c
> +++ b/fs/proc/base.c
> @@ -95,6 +95,9 @@
> #include <linux/sched/stat.h>
> #include <linux/posix-timers.h>
> #include <trace/events/oom.h>
> +#ifdef CONFIG_X86_CPU_RESCTRL
> +#include <asm/resctrl_sched.h>
> +#endif
If anything, this should be abstracted nicely into an
include/linux/resctrl.h header. Other architectures would probably wanna
use it too, I hear ARM64 has something like resctrl.
> #include "internal.h"
> #include "fd.h"
>
> @@ -3060,6 +3063,9 @@ static const struct pid_entry tgid_base_stuff[] = {
> #endif
> #ifdef CONFIG_CGROUPS
> ONE("cgroup", S_IRUGO, proc_cgroup_show),
> +#endif
> +#ifdef CONFIG_X86_CPU_RESCTRL
> + ONE("resctrl", S_IRUGO, proc_resctrl_show),
> #endif
> ONE("oom_score", S_IRUGO, proc_oom_score),
> REG("oom_adj", S_IRUGO|S_IWUSR, proc_oom_adj_operations),
> @@ -3460,6 +3466,9 @@ static const struct pid_entry tid_base_stuff[] = {
> #endif
> #ifdef CONFIG_CGROUPS
> ONE("cgroup", S_IRUGO, proc_cgroup_show),
> +#endif
> +#ifdef CONFIG_X86_CPU_RESCTRL
> + ONE("resctrl", S_IRUGO, proc_resctrl_show),
> #endif
Same here. proc_resctrl_show() looks like a generic function but it
is x86-only. Need to call the x86-specific one in a real generic
proc_resctrl_show() which other arches can add their code to, too.
Not like that.
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
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