From: Joel Fernandes <joel@joelfernandes.org>
To: Chris Hyser <chris.hyser@oracle.com>
Cc: Nishanth Aravamudan <naravamudan@digitalocean.com>,
Julien Desfossez <jdesfossez@digitalocean.com>,
Peter Zijlstra <peterz@infradead.org>,
Tim Chen <tim.c.chen@linux.intel.com>,
Vineeth Pillai <viremana@linux.microsoft.com>,
Aaron Lu <aaron.lwe@gmail.com>,
Aubrey Li <aubrey.intel@gmail.com>,
tglx@linutronix.de, linux-kernel@vger.kernel.org,
mingo@kernel.org, torvalds@linux-foundation.org,
fweisbec@gmail.com, keescook@chromium.org, kerrnel@google.com,
Phil Auld <pauld@redhat.com>,
Valentin Schneider <valentin.schneider@arm.com>,
Mel Gorman <mgorman@techsingularity.net>,
Pawan Gupta <pawan.kumar.gupta@linux.intel.com>,
Paolo Bonzini <pbonzini@redhat.com>,
vineeth@bitbyteword.org, Chen Yu <yu.c.chen@intel.com>,
Christian Brauner <christian.brauner@ubuntu.com>,
Agata Gruza <agata.gruza@intel.com>,
Antonio Gomez Iglesias <antonio.gomez.iglesias@intel.com>,
graf@amazon.com, konrad.wilk@oracle.com, dfaggioli@suse.com,
pjt@google.com, rostedt@goodmis.org, derkling@google.com,
benbjiang@tencent.com,
Alexandre Chartre <alexandre.chartre@oracle.com>,
James.Bottomley@hansenpartnership.com, OWeisse@umich.edu,
Dhaval Giani <dhaval.giani@oracle.com>,
Junaid Shahid <junaids@google.com>,
jsbarnes@google.com, Ben Segall <bsegall@google.com>,
Josh Don <joshdon@google.com>, Hao Luo <haoluo@google.com>,
Tom Lendacky <thomas.lendacky@amd.com>,
Aubrey Li <aubrey.li@linux.intel.com>,
"Paul E. McKenney" <paulmck@kernel.org>,
Tim Chen <tim.c.chen@intel.com>
Subject: Re: [PATCH -tip 23/32] sched: Add a per-thread core scheduling interface
Date: Sun, 6 Dec 2020 12:34:18 -0500 [thread overview]
Message-ID: <20201206173418.GC201514@google.com> (raw)
In-Reply-To: <20201202214717.GA27531@chyser-vm-1.appad1iad.osdevelopmeniad.oraclevcn.com>
On Wed, Dec 02, 2020 at 04:47:17PM -0500, Chris Hyser wrote:
> On Tue, Nov 17, 2020 at 06:19:53PM -0500, Joel Fernandes (Google) wrote:
> > Add a per-thread core scheduling interface which allows a thread to share a
> > core with another thread, or have a core exclusively for itself.
> >
> > ChromeOS uses core-scheduling to securely enable hyperthreading. This cuts
> > down the keypress latency in Google docs from 150ms to 50ms while improving
> > the camera streaming frame rate by ~3%.
> >
>
> Inline is a patch for comment to extend this interface to make it more useful.
> This patch would still need to provide doc and selftests updates as well.
>
> -chrish
>
> ---8<-----------------------
[..]
> diff --git a/include/uapi/linux/prctl.h b/include/uapi/linux/prctl.h
> index 217b048..f8e4e96 100644
> --- a/include/uapi/linux/prctl.h
> +++ b/include/uapi/linux/prctl.h
> @@ -250,5 +250,8 @@ struct prctl_mm_map {
>
> /* Request the scheduler to share a core */
> #define PR_SCHED_CORE_SHARE 59
> +# define PR_SCHED_CORE_CLEAR 0 /* clear core_sched cookie of pid */
> +# define PR_SCHED_CORE_SHARE_FROM 1 /* get core_sched cookie from pid */
> +# define PR_SCHED_CORE_SHARE_TO 2 /* push core_sched cookie to pid */
>
> #endif /* _LINUX_PRCTL_H */
> diff --git a/kernel/sched/coretag.c b/kernel/sched/coretag.c
> index 800c0f8..14feac1 100644
> --- a/kernel/sched/coretag.c
> +++ b/kernel/sched/coretag.c
> @@ -9,6 +9,7 @@
> */
>
> #include "sched.h"
> +#include "linux/prctl.h"
>
> /*
> * Wrapper representing a complete cookie. The address of the cookie is used as
> @@ -456,40 +457,45 @@ int sched_core_share_tasks(struct task_struct *t1, struct task_struct *t2)
> }
>
> /* Called from prctl interface: PR_SCHED_CORE_SHARE */
> -int sched_core_share_pid(pid_t pid)
> +int sched_core_share_pid(unsigned long flags, pid_t pid)
> {
> + struct task_struct *dest;
> + struct task_struct *src;
> struct task_struct *task;
> int err;
>
> - if (pid == 0) { /* Recent current task's cookie. */
> - /* Resetting a cookie requires privileges. */
> - if (current->core_task_cookie)
> - if (!capable(CAP_SYS_ADMIN))
> - return -EPERM;
> - task = NULL;
> - } else {
> - rcu_read_lock();
> - task = pid ? find_task_by_vpid(pid) : current;
> - if (!task) {
> - rcu_read_unlock();
> - return -ESRCH;
> - }
> -
> - get_task_struct(task);
> -
> - /*
> - * Check if this process has the right to modify the specified
> - * process. Use the regular "ptrace_may_access()" checks.
> - */
> - if (!ptrace_may_access(task, PTRACE_MODE_READ_REALCREDS)) {
> - rcu_read_unlock();
> - err = -EPERM;
> - goto out;
> - }
> + rcu_read_lock();
> + task = find_task_by_vpid(pid);
> + if (!task) {
> rcu_read_unlock();
> + return -ESRCH;
> }
>
> - err = sched_core_share_tasks(current, task);
> + get_task_struct(task);
> +
> + /*
> + * Check if this process has the right to modify the specified
> + * process. Use the regular "ptrace_may_access()" checks.
> + */
> + if (!ptrace_may_access(task, PTRACE_MODE_READ_REALCREDS)) {
> + rcu_read_unlock();
> + err = -EPERM;
> + goto out;
> + }
> + rcu_read_unlock();
> +
> + if (flags == PR_SCHED_CORE_CLEAR) {
> + dest = task;
> + src = NULL;
> + } else if (flags == PR_SCHED_CORE_SHARE_TO) {
> + dest = task;
> + src = current;
> + } else if (flags == PR_SCHED_CORE_SHARE_FROM) {
> + dest = current;
> + src = task;
> + }
Looks ok to me except the missing else { } clause you found. Also, maybe
dest/src can be renamed to from/to to make meaning of variables more clear?
Also looking forward to the docs/test updates.
thanks!
- Joel
> +
> + err = sched_core_share_tasks(dest, src);
> out:
> if (task)
> put_task_struct(task);
> diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
> index cffdfab..50c31f3 100644
> --- a/kernel/sched/debug.c
> +++ b/kernel/sched/debug.c
> @@ -1030,6 +1030,7 @@ void proc_sched_show_task(struct task_struct *p, struct pid_namespace *ns,
>
> #ifdef CONFIG_SCHED_CORE
> __PS("core_cookie", p->core_cookie);
> + __PS("core_task_cookie", p->core_task_cookie);
> #endif
>
> sched_show_numa(p, m);
> diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
> index b3b89bd..eafb399 100644
> --- a/kernel/sched/sched.h
> +++ b/kernel/sched/sched.h
> @@ -1202,7 +1202,7 @@ void sched_core_dequeue(struct rq *rq, struct task_struct *p);
> void sched_core_get(void);
> void sched_core_put(void);
>
> -int sched_core_share_pid(pid_t pid);
> +int sched_core_share_pid(unsigned long flags, pid_t pid);
> int sched_core_share_tasks(struct task_struct *t1, struct task_struct *t2);
>
> #ifdef CONFIG_CGROUP_SCHED
> diff --git a/kernel/sys.c b/kernel/sys.c
> index 61a3c98..da52a0d 100644
> --- a/kernel/sys.c
> +++ b/kernel/sys.c
> @@ -2530,9 +2530,13 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3,
>
> error = (current->flags & PR_IO_FLUSHER) == PR_IO_FLUSHER;
> break;
> +#ifdef CONFIG_SCHED_CORE
> case PR_SCHED_CORE_SHARE:
> - error = sched_core_share_pid(arg2);
> + if (arg4 || arg5)
> + return -EINVAL;
> + error = sched_core_share_pid(arg2, arg3);
> break;
> +#endif
> default:
> error = -EINVAL;
> break;
next prev parent reply other threads:[~2020-12-06 17:35 UTC|newest]
Thread overview: 150+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-17 23:19 [PATCH -tip 00/32] Core scheduling (v9) Joel Fernandes (Google)
2020-11-17 23:19 ` [PATCH -tip 01/32] sched: Wrap rq::lock access Joel Fernandes (Google)
2020-11-19 23:31 ` Singh, Balbir
2020-11-20 16:55 ` Joel Fernandes
2020-11-22 8:52 ` Balbir Singh
2020-11-17 23:19 ` [PATCH -tip 02/32] sched: Introduce sched_class::pick_task() Joel Fernandes (Google)
2020-11-19 23:56 ` Singh, Balbir
2020-11-20 16:58 ` Joel Fernandes
2020-11-25 23:19 ` Balbir Singh
2020-11-25 16:28 ` Vincent Guittot
2020-11-26 9:07 ` Peter Zijlstra
2020-11-26 10:17 ` Vincent Guittot
2020-11-26 12:40 ` Peter Zijlstra
2020-11-17 23:19 ` [PATCH -tip 03/32] sched/fair: Fix pick_task_fair crashes due to empty rbtree Joel Fernandes (Google)
2020-11-20 10:15 ` Singh, Balbir
2020-11-20 18:11 ` Vineeth Pillai
2020-11-23 22:31 ` Balbir Singh
2020-11-24 8:31 ` Peter Zijlstra
2020-11-17 23:19 ` [PATCH -tip 04/32] sched: Core-wide rq->lock Joel Fernandes (Google)
2020-11-22 9:11 ` Balbir Singh
2020-11-24 8:16 ` Peter Zijlstra
2020-11-26 0:35 ` Balbir Singh
2020-11-17 23:19 ` [PATCH -tip 05/32] sched/fair: Add a few assertions Joel Fernandes (Google)
2020-11-17 23:19 ` [PATCH -tip 06/32] sched: Basic tracking of matching tasks Joel Fernandes (Google)
2020-11-17 23:19 ` [PATCH -tip 07/32] sched: Add core wide task selection and scheduling Joel Fernandes (Google)
2020-11-17 23:19 ` [PATCH -tip 08/32] sched/fair: Fix forced idle sibling starvation corner case Joel Fernandes (Google)
2020-11-22 10:35 ` Balbir Singh
2020-11-17 23:19 ` [PATCH -tip 09/32] sched/fair: Snapshot the min_vruntime of CPUs on force idle Joel Fernandes (Google)
2020-11-22 11:44 ` Balbir Singh
2020-11-23 12:31 ` Vineeth Pillai
2020-11-23 23:31 ` Balbir Singh
2020-11-24 9:09 ` Peter Zijlstra
2020-11-25 23:17 ` Balbir Singh
2020-11-26 8:23 ` Peter Zijlstra
2020-11-17 23:19 ` [PATCH -tip 10/32] sched: Fix priority inversion of cookied task with sibling Joel Fernandes (Google)
2020-11-22 22:41 ` Balbir Singh
2020-11-24 18:30 ` Joel Fernandes
2020-11-25 23:05 ` Balbir Singh
2020-11-26 8:29 ` Peter Zijlstra
2020-11-26 22:27 ` Balbir Singh
2020-12-01 17:49 ` Joel Fernandes
2020-11-17 23:19 ` [PATCH -tip 11/32] sched: Enqueue task into core queue only after vruntime is updated Joel Fernandes (Google)
2020-11-17 23:19 ` [PATCH -tip 12/32] sched: Simplify the core pick loop for optimized case Joel Fernandes (Google)
2020-11-24 12:04 ` Peter Zijlstra
2020-11-24 17:04 ` Joel Fernandes
2020-11-25 8:37 ` Peter Zijlstra
2020-11-17 23:19 ` [PATCH -tip 13/32] sched: Trivial forced-newidle balancer Joel Fernandes (Google)
2020-11-23 4:38 ` Balbir Singh
2020-11-23 15:07 ` Li, Aubrey
2020-11-23 23:35 ` Balbir Singh
2020-11-24 0:32 ` Li, Aubrey
2020-11-25 21:28 ` Balbir Singh
2020-11-17 23:19 ` [PATCH -tip 14/32] sched: migration changes for core scheduling Joel Fernandes (Google)
2020-11-22 23:54 ` Balbir Singh
2020-11-23 4:36 ` Li, Aubrey
2020-11-24 15:42 ` Peter Zijlstra
2020-11-25 3:12 ` Li, Aubrey
2020-11-25 22:57 ` Balbir Singh
2020-11-26 3:20 ` Li, Aubrey
2020-11-26 8:32 ` Balbir Singh
2020-11-26 9:26 ` Li, Aubrey
2020-11-30 9:33 ` Balbir Singh
2020-11-30 12:29 ` Li, Aubrey
2020-12-02 14:09 ` Li, Aubrey
2020-12-03 1:06 ` Li, Aubrey
2020-11-30 10:35 ` Vincent Guittot
2020-11-30 12:32 ` Li, Aubrey
2020-11-17 23:19 ` [PATCH -tip 15/32] sched: Improve snapshotting of min_vruntime for CGroups Joel Fernandes (Google)
2020-11-24 10:27 ` Peter Zijlstra
2020-11-24 17:07 ` Joel Fernandes
2020-11-25 8:41 ` Peter Zijlstra
2020-11-24 10:41 ` Peter Zijlstra
2020-11-17 23:19 ` [PATCH -tip 16/32] irq_work: Cleanup Joel Fernandes (Google)
2020-11-17 23:19 ` [PATCH -tip 17/32] arch/x86: Add a new TIF flag for untrusted tasks Joel Fernandes (Google)
2020-11-23 5:18 ` Balbir Singh
2020-11-17 23:19 ` [PATCH -tip 18/32] kernel/entry: Add support for core-wide protection of kernel-mode Joel Fernandes (Google)
2020-11-24 16:09 ` Peter Zijlstra
2020-11-24 17:52 ` Joel Fernandes
2020-11-25 9:37 ` Peter Zijlstra
2020-12-01 17:55 ` Joel Fernandes
2020-11-26 5:37 ` Balbir Singh
2020-11-17 23:19 ` [PATCH -tip 19/32] entry/idle: Enter and exit kernel protection during idle entry and exit Joel Fernandes (Google)
2020-11-24 16:13 ` Peter Zijlstra
2020-11-24 18:03 ` Joel Fernandes
2020-11-25 8:49 ` Peter Zijlstra
2020-12-01 18:24 ` Joel Fernandes
2020-11-17 23:19 ` [PATCH -tip 20/32] entry/kvm: Protect the kernel when entering from guest Joel Fernandes (Google)
2020-11-17 23:19 ` [PATCH -tip 21/32] sched: CGroup tagging interface for core scheduling Joel Fernandes (Google)
2020-11-17 23:19 ` [PATCH -tip 22/32] sched: Split the cookie and setup per-task cookie on fork Joel Fernandes (Google)
2020-11-25 11:07 ` Peter Zijlstra
2020-12-01 18:56 ` Joel Fernandes
2020-11-25 11:10 ` Peter Zijlstra
2020-12-01 19:20 ` Joel Fernandes
2020-12-01 19:34 ` Peter Zijlstra
2020-12-02 6:36 ` Josh Don
2020-12-02 7:54 ` Peter Zijlstra
2020-12-04 0:20 ` Josh Don
2020-12-06 17:49 ` Joel Fernandes
2020-11-25 11:11 ` Peter Zijlstra
2020-12-01 19:16 ` Joel Fernandes
2020-11-25 11:15 ` Peter Zijlstra
2020-12-01 19:11 ` Joel Fernandes
2020-12-01 19:20 ` Peter Zijlstra
2020-12-06 18:15 ` Joel Fernandes
2020-11-25 12:54 ` Peter Zijlstra
2020-12-01 18:38 ` Joel Fernandes
2020-11-25 13:03 ` Peter Zijlstra
2020-12-01 18:52 ` Joel Fernandes
2020-11-30 23:05 ` Balbir Singh
2020-11-17 23:19 ` [PATCH -tip 23/32] sched: Add a per-thread core scheduling interface Joel Fernandes (Google)
2020-11-25 13:08 ` Peter Zijlstra
2020-12-01 19:36 ` Joel Fernandes
2020-12-02 21:47 ` Chris Hyser
2020-12-02 23:13 ` chris hyser
2020-12-06 17:34 ` Joel Fernandes [this message]
2020-12-07 21:48 ` chris hyser
2020-12-09 18:52 ` Chris Hyser
2020-12-14 19:31 ` Joel Fernandes
2020-12-14 19:44 ` chris hyser
2020-12-14 23:25 ` Joel Fernandes
2020-12-15 14:56 ` chris hyser
2020-12-15 16:23 ` chris hyser
2020-12-15 18:13 ` Dhaval Giani
2020-12-16 0:35 ` Joel Fernandes
2020-11-17 23:19 ` [PATCH -tip 24/32] sched: Release references to the per-task cookie on exit Joel Fernandes (Google)
2020-11-25 13:03 ` Peter Zijlstra
2020-11-17 23:19 ` [PATCH -tip 25/32] sched: Refactor core cookie into struct Joel Fernandes (Google)
2020-11-17 23:19 ` [PATCH -tip 26/32] sched: Add a second-level tag for nested CGroup usecase Joel Fernandes (Google)
2020-11-25 13:42 ` Peter Zijlstra
2020-11-30 23:10 ` Balbir Singh
2020-12-01 20:08 ` Joel Fernandes
2020-12-02 6:18 ` Josh Don
2020-12-02 8:02 ` Peter Zijlstra
2020-12-02 18:53 ` Tejun Heo
2020-12-04 0:51 ` Josh Don
2020-12-04 15:45 ` Tejun Heo
2020-11-17 23:19 ` [PATCH -tip 27/32] sched/debug: Add CGroup node for printing group cookie if SCHED_DEBUG Joel Fernandes (Google)
2020-11-17 23:19 ` [PATCH -tip 28/32] kselftest: Add tests for core-sched interface Joel Fernandes (Google)
2020-11-17 23:19 ` [PATCH -tip 29/32] sched: Move core-scheduler interfacing code to a new file Joel Fernandes (Google)
2020-11-17 23:20 ` [PATCH -tip 30/32] Documentation: Add core scheduling documentation Joel Fernandes (Google)
2020-11-17 23:20 ` [PATCH -tip 31/32] sched: Add a coresched command line option Joel Fernandes (Google)
2020-11-19 23:39 ` Randy Dunlap
2020-11-25 13:45 ` Peter Zijlstra
2020-11-26 0:11 ` Balbir Singh
2020-11-17 23:20 ` [PATCH -tip 32/32] sched: Debug bits Joel Fernandes (Google)
2020-12-01 0:21 ` Balbir Singh
2021-01-15 15:10 ` Joel Fernandes
2020-11-24 11:48 ` [PATCH -tip 00/32] Core scheduling (v9) Vincent Guittot
2020-11-24 15:08 ` Joel Fernandes
2020-12-03 6:16 ` Ning, Hongyu
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