Re: 2.5.65-mm2

Ed Tomlinson
2003-03-20T04:16:29Z

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On March 19, 2003 06:45 pm, Steven P. Cole wrote:
> On Wed, 2003-03-19 at 17:33, Andrew Morton wrote:
> > "Steven P. Cole" <elenstev@mesatop.com> wrote:
> > > > Summary: using ext3, the simple window shake and scrollbar wiggle
> > > > tests were much improved, but really using Evolution left much to be
> > > > desired.
> > >
> > > Replying to myself for a followup,
> > >
> > > I repeated the tests with 2.5.65-mm2 elevator=deadline and the
> > > situation was similar to elevator=as. Running dbench on ext3, the
> > > response to desktop switches and window wiggles was improved over
> > > running dbench on reiserfs, but typing in Evolution was subject to long
> > > delays with dbench clients greater than 16.
> >
> > OK, final question before I get off my butt and find a way to reproduce
> > this:
> >
> > Does reverting
> >
> > http://www.zip.com.au/~akpm/linux/patches/2.5/2.5.65/2.5.65-mm2/broken-ou
> >t/sched-2.5.64-D3.patch
> >
> > help?
>
> Sorry, didn't have much time for a lot of testing, but no miracles
> occurred. With 5 minutes of testing 2.5.65-mm2 and dbench 24 on ext3
> and that patch reverted (first hunk had to be manually fixed), I don't
> see any improvement. Still the same long long delays in trying to use
> Evolution.

Steven,

Do things improve with the patch below applied? You have to backout the
schedule-tuneables patch before appling it.

Ed Tomlinson

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# This is a BitKeeper generated patch for the following project:
# Project Name: Linux kernel tree
# This patch format is intended for GNU patch command version 2.5 or higher.
# This patch includes the following deltas:
# ChangeSet 1.1087 -> 1.1088
# include/linux/sched.h 1.137 -> 1.138
# kernel/fork.c 1.112 -> 1.113
# kernel/user.c 1.6 -> 1.7
# kernel/sched.c 1.163 -> 1.164
#
# The following is the BitKeeper ChangeSet Log
# --------------------------------------------
# 03/03/07 ed@oscar.et.ca 1.1088
# Add user and thread group governors to prevent either from monoplizing
# the system. The governors work by limiting the sum of the timeslices
# of active tasks in a group to <n> timeslices. The defaults set <n> to
# 1.5 for thread groups and to 10 for user tasks.
#
# For numa systems the governors are per node. Idealy the storage
# should also be local to the node however, we do not have dynamic per
# node storage yet...
# --------------------------------------------
#
diff -Nru a/include/linux/sched.h b/include/linux/sched.h
--- a/include/linux/sched.h Sat Mar 8 14:18:48 2003
+++ b/include/linux/sched.h Sat Mar 8 14:18:48 2003
@@ -178,6 +178,11 @@

#include <linux/aio.h>

+struct ptg_struct { /* pseudo thread groups */
+ atomic_t active[MAX_NUMNODES];
+ atomic_t count; /* number of refs */
+};
+
struct mm_struct {
struct vm_area_struct * mmap; /* list of VMAs */
struct rb_root mm_rb;
@@ -278,6 +283,7 @@
struct user_struct {
atomic_t __count; /* reference count */
atomic_t processes; /* How many processes does this user have? */
+ atomic_t active[MAX_NUMNODES];
atomic_t files; /* How many open files does this user have? */

/* Hash table maintenance information */
@@ -344,6 +350,8 @@
struct list_head ptrace_list;

struct mm_struct *mm, *active_mm;
+ struct ptg_struct * ptgroup; /* pseudo thread group for this task */
+ atomic_t *governor; /* the atomic_t that governs this task */

/* task state */
struct linux_binfmt *binfmt;
diff -Nru a/kernel/fork.c b/kernel/fork.c
--- a/kernel/fork.c Sat Mar 8 14:18:48 2003
+++ b/kernel/fork.c Sat Mar 8 14:18:48 2003
@@ -96,12 +96,24 @@
}
}

+void free_ptgroup(struct task_struct *tsk)
+{
+ if (tsk->ptgroup && atomic_sub_and_test(1,&tsk->ptgroup->count)) {
+ kfree(tsk->ptgroup);
+ tsk->ptgroup = NULL;
+ tsk->governor = &tsk->user->active[cpu_to_node(task_cpu(tsk))];
+ if (tsk == current)
+ atomic_inc(tsk->governor);
+ }
+}
+
void __put_task_struct(struct task_struct *tsk)
{
WARN_ON(!(tsk->state & (TASK_DEAD | TASK_ZOMBIE)));
WARN_ON(atomic_read(&tsk->usage));
WARN_ON(tsk == current);

+ free_ptgroup(tsk);
security_task_free(tsk);
free_uid(tsk->user);
free_task_struct(tsk);
@@ -469,6 +481,7 @@

tsk->mm = NULL;
tsk->active_mm = NULL;
+ tsk->ptgroup = NULL;

/*
* Are we cloning a kernel thread?
@@ -734,6 +747,32 @@
p->flags = new_flags;
}

+static inline int setup_governor(unsigned long clone_flags, struct task_struct *p)
+{
+ if ( ((clone_flags & CLONE_VM) && (clone_flags & CLONE_FILES)) ||
+ (clone_flags & CLONE_THREAD)) {
+ if (current->ptgroup)
+ atomic_inc(&current->ptgroup->count);
+ else {
+ int i;
+ current->ptgroup = kmalloc(sizeof(struct ptg_struct), GFP_ATOMIC);
+ if (!current->ptgroup)
+ return 1;
+ /* printk(KERN_INFO "ptgroup - pid %u\n",current->pid); */
+ atomic_set(&current->ptgroup->count,2);
+ for(i=0; i < MAX_NUMNODES; i++)
+ atomic_set(&current->ptgroup->active[i], 0);
+ atomic_set(&current->ptgroup->active[numa_node_id()], 1);
+ atomic_dec(current->governor);
+ current->governor = &current->ptgroup->active[numa_node_id()];
+ }
+ p->ptgroup = current->ptgroup;
+ p->governor = &p->ptgroup->active[numa_node_id()];
+ } else
+ p->governor = &p->user->active[numa_node_id()];
+ return 0;
+}
+
asmlinkage int sys_set_tid_address(int *tidptr)
{
current->clear_child_tid = tidptr;
@@ -876,6 +915,12 @@
goto bad_fork_cleanup_mm;
retval = copy_thread(0, clone_flags, stack_start, stack_size, p, regs);
if (retval)
+ goto bad_fork_cleanup_namespace;
+ /*
+ * Setup the governor pointer for the new process, allocating a new ptg as
+ * required if the process is a thread.
+ */
+ if (setup_governor(clone_flags, p))
goto bad_fork_cleanup_namespace;

if (clone_flags & CLONE_CHILD_SETTID)
diff -Nru a/kernel/sched.c b/kernel/sched.c
--- a/kernel/sched.c Sat Mar 8 14:18:48 2003
+++ b/kernel/sched.c Sat Mar 8 14:18:48 2003
@@ -68,6 +68,9 @@
#define MAX_SLEEP_AVG (10*HZ)
#define STARVATION_LIMIT (10*HZ)
#define NODE_THRESHOLD 125
+#define THREAD_GOVERNOR 15 /* allow threads groups 1.5 full timeslices */
+#define USER_GOVERNOR 100 /* allow user 10 full timeslices */
+

/*
* If a task is 'interactive' then we reinsert it in the active
@@ -123,7 +126,26 @@

static inline unsigned int task_timeslice(task_t *p)
{
- return BASE_TIMESLICE(p);
+ int slice = BASE_TIMESLICE(p);
+ int threads = atomic_read(p->governor) * 10;
+ int govern = threads;
+ if (p->user->uid)
+ govern = (p->ptgroup) ? THREAD_GOVERNOR : USER_GOVERNOR;
+ if (threads > govern) {
+ slice = (slice * govern) / threads;
+ slice = (slice > MIN_TIMESLICE) ? slice : MIN_TIMESLICE;
+ }
+#if 0
+ {
+ static int next;
+ if (time_after(jiffies, next)) {
+ printk(KERN_INFO "uid %d pid %d nod %d ptg %x gov %x threads %d lim %d slice %d\n",
+ p->uid, p->pid, numa_node_id(), p->ptgroup, p->governor, threads/10, govern, slice);
+ next = jiffies + HZ*300;
+ }
+ }
+#endif
+ return slice;
}

/*
@@ -197,16 +219,18 @@
rq->node_nr_running = &node_nr_running[0];
}

-static inline void nr_running_inc(runqueue_t *rq)
+static inline void nr_running_inc(task_t *p, runqueue_t *rq)
{
atomic_inc(rq->node_nr_running);
rq->nr_running++;
+ atomic_inc(p->governor);
}

-static inline void nr_running_dec(runqueue_t *rq)
+static inline void nr_running_dec(task_t *p, runqueue_t *rq)
{
atomic_dec(rq->node_nr_running);
rq->nr_running--;
+ atomic_dec(p->governor);
}

__init void node_nr_running_init(void)
@@ -220,8 +244,8 @@
#else /* !CONFIG_NUMA */

# define nr_running_init(rq) do { } while (0)
-# define nr_running_inc(rq) do { (rq)->nr_running++; } while (0)
-# define nr_running_dec(rq) do { (rq)->nr_running--; } while (0)
+# define nr_running_inc(p, rq) do { (rq)->nr_running++; atomic_inc((p)->governor); } while (0)
+# define nr_running_dec(p, rq) do { (rq)->nr_running--; atomic_dec((p)->governor); } while (0)

#endif /* CONFIG_NUMA */

@@ -326,7 +350,7 @@
static inline void __activate_task(task_t *p, runqueue_t *rq)
{
enqueue_task(p, rq->active);
- nr_running_inc(rq);
+ nr_running_inc(p, rq);
}

/*
@@ -387,7 +411,7 @@
*/
static inline void deactivate_task(struct task_struct *p, runqueue_t *rq)
{
- nr_running_dec(rq);
+ nr_running_dec(p, rq);
if (p->state == TASK_UNINTERRUPTIBLE)
rq->nr_uninterruptible++;
dequeue_task(p, p->array);
@@ -586,7 +610,7 @@
list_add_tail(&p->run_list, &current->run_list);
p->array = current->array;
p->array->nr_active++;
- nr_running_inc(rq);
+ nr_running_inc(p, rq);
}
task_rq_unlock(rq, &flags);
}
@@ -1004,9 +1028,15 @@
static inline void pull_task(runqueue_t *src_rq, prio_array_t *src_array, task_t *p, runqueue_t *this_rq, int this_cpu)
{
dequeue_task(p, src_array);
- nr_running_dec(src_rq);
+ nr_running_dec(p, src_rq);
set_task_cpu(p, this_cpu);
- nr_running_inc(this_rq);
+#ifdef CONFIG_NUMA
+ if (p->ptgroup)
+ p->governor = &p->ptgroup->active[cpu_to_node(this_cpu)];
+ else
+ p->governor = &p->user->active[cpu_to_node(this_cpu)];
+#endif
+ nr_running_inc(p, this_rq);
enqueue_task(p, this_rq->active);
/*
* Note that idle threads have a prio of MAX_PRIO, for this test
@@ -2521,6 +2551,8 @@
rq->curr = current;
rq->idle = current;
set_task_cpu(current, smp_processor_id());
+ current->governor = &current->user->active[numa_node_id()];
+ atomic_inc(current->governor);
wake_up_forked_process(current);
current->prio = MAX_PRIO;

diff -Nru a/kernel/user.c b/kernel/user.c
--- a/kernel/user.c Sat Mar 8 14:18:48 2003
+++ b/kernel/user.c Sat Mar 8 14:18:48 2003
@@ -30,6 +30,7 @@
struct user_struct root_user = {
.__count = ATOMIC_INIT(1),
.processes = ATOMIC_INIT(1),
+ .active = {[0 ...MAX_NUMNODES-1] = ATOMIC_INIT(0)},
.files = ATOMIC_INIT(0)
};

@@ -89,6 +90,7 @@

if (!up) {
struct user_struct *new;
+ int i;

new = kmem_cache_alloc(uid_cachep, SLAB_KERNEL);
if (!new)
@@ -96,6 +98,8 @@
new->uid = uid;
atomic_set(&new->__count, 1);
atomic_set(&new->processes, 0);
+ for(i=0; i < MAX_NUMNODES; i++)
+ atomic_set(&new->active[i], 0);
atomic_set(&new->files, 0);

/*
@@ -130,6 +134,11 @@
atomic_inc(&new_user->processes);
atomic_dec(&old_user->processes);
current->user = new_user;
+ if (!current->ptgroup) {
+ atomic_dec(current->governor);
+ current->governor = &current->user->active[numa_node_id()];
+ atomic_inc(current->governor);
+ }
free_uid(old_user);
}