Re: [ckrm-tech] [RFC][PATCH 3/7] UBC: ub context and inheritance

Kirill Korotaev
2006-08-18T09:21:05Z

Matt Helsley wrote:
> On Wed, 2006-08-16 at 19:38 +0400, Kirill Korotaev wrote:
>
>>Contains code responsible for setting UB on task,
>>it's inheriting and setting host context in interrupts.
>>
>>Task references three beancounters:
>> 1. exec_ub current context. all resources are
>> charged to this beancounter.
>
>
> nit: 2-3 below seem to contradict "all". If you mean "the rest" then
> perhaps you ought to reorder these:
>
> 1. task_ub ...
> 2. fork_sub ...
> 3. exec_ub Current context. Resources not charged to task_ub
> or fork_sub are charged to this beancounter.
not sure what you mean.
task_ub - where _task_ _itself_ is charged as an object.
following patches will add charging of "number of tasks" using it.
fork_sub - beancounter which is inherited on fork() (chaning task beancounter).
exec_ub - is current context.

>> 2. task_ub beancounter to which task_struct is
>> charged itself.
>
>
> Is task_ub frequently the parent beancounter of exec_ub? If it's always
> the parent then perhaps the one or more of these _ub fields in the task
> struct are not necessary.
no, task_ub != exec_ub of parent task
when task is created anything can happen: task can change ub, parent can change ub,
task can be reparented. But the UB we charged task to should be known.

> Also in that case keeping copies of the
> "parent" user_beancounter pointers in the task_beancounters would seem
> bug-prone -- if the hierarchy of beancounters changes then these would
> need to be changed too.
>
>
>> 3. fork_sub beancounter which is inherited by
>> task's children on fork
>
>
> Is this frequently the same as exec_ub?
frequently, but not always. exec_ub is changed in softirq for example.
consider exec_ub as 'current' pointer in kernel.

see other comments below

>>Signed-Off-By: Pavel Emelianov <xemul@sw.ru>
>>Signed-Off-By: Kirill Korotaev <dev@sw.ru>
>>
>>---
>> include/linux/sched.h | 5 +++++
>> include/ub/task.h | 42 ++++++++++++++++++++++++++++++++++++++++++
>> kernel/fork.c | 21 ++++++++++++++++-----
>> kernel/irq/handle.c | 9 +++++++++
>> kernel/softirq.c | 8 ++++++++
>> kernel/ub/Makefile | 1 +
>> kernel/ub/beancounter.c | 4 ++++
>> kernel/ub/misc.c | 34 ++++++++++++++++++++++++++++++++++
>> 8 files changed, 119 insertions(+), 5 deletions(-)
>>
>>--- ./include/linux/sched.h.ubfork 2006-07-17 17:01:12.000000000 +0400
>>+++ ./include/linux/sched.h 2006-07-31 16:01:54.000000000 +0400
>>@@ -81,6 +81,8 @@ struct sched_param {
>> #include <linux/timer.h>
>> #include <linux/hrtimer.h>
>>
>>+#include <ub/task.h>
>>+
>> #include <asm/processor.h>
>>
>> struct exec_domain;
>>@@ -997,6 +999,9 @@ struct task_struct {
>> spinlock_t delays_lock;
>> struct task_delay_info *delays;
>> #endif
>>+#ifdef CONFIG_USER_RESOURCE
>>+ struct task_beancounter task_bc;
>>+#endif
>> };
>>
>> static inline pid_t process_group(struct task_struct *tsk)
>>--- ./include/ub/task.h.ubfork 2006-07-28 18:53:52.000000000 +0400
>>+++ ./include/ub/task.h 2006-08-01 15:26:08.000000000 +0400
>>@@ -0,0 +1,42 @@
>>+/*
>>+ * include/ub/task.h
>>+ *
>>+ * Copyright (C) 2006 OpenVZ. SWsoft Inc
>>+ *
>>+ */
>>+
>>+#ifndef __UB_TASK_H_
>>+#define __UB_TASK_H_
>>+
>>+#include <linux/config.h>
>>+
>>+struct user_beancounter;
>>+
>>+struct task_beancounter {
>>+ struct user_beancounter *exec_ub;
>>+ struct user_beancounter *task_ub;
>>+ struct user_beancounter *fork_sub;
>>+};
>>+
>>+#ifdef CONFIG_USER_RESOURCE
>>+#define get_exec_ub() (current->task_bc.exec_ub)
>>+#define set_exec_ub(newub) \
>>+ ({ \
>>+ struct user_beancounter *old; \
>>+ struct task_beancounter *tbc; \
>>+ tbc = &current->task_bc; \
>>+ old = tbc->exec_ub; \
>>+ tbc->exec_ub = newub; \
>>+ old; \
>>+ })
>>+
>
>
> How about making these static inlines?
possible, but this requires including sched.h, which includes this file...
so this one is easier and more separated.

>>+int ub_task_charge(struct task_struct *parent, struct task_struct *new);
>>+void ub_task_uncharge(struct task_struct *tsk);
>>+
>>+#else /* CONFIG_USER_RESOURCE */
>>+#define get_exec_ub() (NULL)
>>+#define set_exec_ub(__ub) (NULL)
>>+#define ub_task_charge(p, t) (0)
>>+#define ub_task_uncharge(t) do { } while (0)
>>+#endif /* CONFIG_USER_RESOURCE */
>>+#endif /* __UB_TASK_H_ */
>>--- ./kernel/irq/handle.c.ubirq 2006-07-10 12:39:20.000000000 +0400
>>+++ ./kernel/irq/handle.c 2006-08-01 12:39:34.000000000 +0400
>>@@ -16,6 +16,9 @@
>> #include <linux/interrupt.h>
>> #include <linux/kernel_stat.h>
>>
>>+#include <ub/beancounter.h>
>>+#include <ub/task.h>
>>+
>> #include "internals.h"
>>
>> /**
>>@@ -166,6 +169,9 @@ fastcall unsigned int __do_IRQ(unsigned
>> struct irq_desc *desc = irq_desc + irq;
>> struct irqaction *action;
>> unsigned int status;
>>+ struct user_beancounter *ub;
>>+
>>+ ub = set_exec_ub(&ub0);
>
>
> Perhaps a comment: "/* Don't charge resources gained in interrupts to current */
ok, will add comment:
/* UBC charges should be done to host system */
>
>
>> kstat_this_cpu.irqs[irq]++;
>> if (CHECK_IRQ_PER_CPU(desc->status)) {
>>@@ -178,6 +184,8 @@ fastcall unsigned int __do_IRQ(unsigned
>> desc->chip->ack(irq);
>> action_ret = handle_IRQ_event(irq, regs, desc->action);
>> desc->chip->end(irq);
>>+
>>+ (void) set_exec_ub(ub);
>> return 1;
>> }
>>
>>@@ -246,6 +254,7 @@ out:
>> desc->chip->end(irq);
>> spin_unlock(&desc->lock);
>>
>>+ (void) set_exec_ub(ub);
>
>
>
> Seems like a WARN_ON() would be appropriate rather than ignoring the
> return code.
BUG_ON(ret != &ub0) ?

maybe introduce a kind of
reset_exec_ub(old_ub, expected_current_ub)
{
ret = set_exec_ub(old_ub);
BUG_ON(ret != expected_current_ub);
}
?

>> return 1;
>> }
>>
>>--- ./kernel/softirq.c.ubirq 2006-07-17 17:01:12.000000000 +0400
>>+++ ./kernel/softirq.c 2006-08-01 12:40:44.000000000 +0400
>>@@ -18,6 +18,9 @@
>> #include <linux/rcupdate.h>
>> #include <linux/smp.h>
>>
>>+#include <ub/beancounter.h>
>>+#include <ub/task.h>
>>+
>> #include <asm/irq.h>
>> /*
>> - No shared variables, all the data are CPU local.
>>@@ -191,6 +194,9 @@ asmlinkage void __do_softirq(void)
>> __u32 pending;
>> int max_restart = MAX_SOFTIRQ_RESTART;
>> int cpu;
>>+ struct user_beancounter *ub;
>>+
>>+ ub = set_exec_ub(&ub0);
>
>
> Perhaps add the same comment...
ok

>
>
>> pending = local_softirq_pending();
>> account_system_vtime(current);
>>@@ -229,6 +235,8 @@ restart:
>>
>> account_system_vtime(current);
>> _local_bh_enable();
>>+
>>+ (void) set_exec_ub(ub);
>
>
> .. and the same WARN_ON.
>
>
>> }
>>
>> #ifndef __ARCH_HAS_DO_SOFTIRQ
>>--- ./kernel/fork.c.ubfork 2006-07-17 17:01:12.000000000 +0400
>>+++ ./kernel/fork.c 2006-08-01 12:58:36.000000000 +0400
>>@@ -46,6 +46,8 @@
>> #include <linux/delayacct.h>
>> #include <linux/taskstats_kern.h>
>>
>>+#include <ub/task.h>
>>+
>> #include <asm/pgtable.h>
>> #include <asm/pgalloc.h>
>> #include <asm/uaccess.h>
>>@@ -102,6 +104,7 @@ static kmem_cache_t *mm_cachep;
>>
>> void free_task(struct task_struct *tsk)
>> {
>>+ ub_task_uncharge(tsk);
>> free_thread_info(tsk->thread_info);
>> rt_mutex_debug_task_free(tsk);
>> free_task_struct(tsk);
>>@@ -162,18 +165,19 @@ static struct task_struct *dup_task_stru
>>
>> tsk = alloc_task_struct();
>> if (!tsk)
>>- return NULL;
>>+ goto out;
>>
>> ti = alloc_thread_info(tsk);
>>- if (!ti) {
>>- free_task_struct(tsk);
>>- return NULL;
>>- }
>>+ if (!ti)
>>+ goto out_tsk;
>>
>> *tsk = *orig;
>> tsk->thread_info = ti;
>> setup_thread_stack(tsk, orig);
>>
>>+ if (ub_task_charge(orig, tsk))
>>+ goto out_ti;
>>+
>> /* One for us, one for whoever does the "release_task()" (usually parent) */
>> atomic_set(&tsk->usage,2);
>> atomic_set(&tsk->fs_excl, 0);
>>@@ -180,6 +184,13 @@ static struct task_struct *dup_task_stru
>> #endif
>> tsk->splice_pipe = NULL;
>> return tsk;
>>+
>>+out_ti:
>>+ free_thread_info(ti);
>>+out_tsk:
>>+ free_task_struct(tsk);
>>+out:
>>+ return NULL;
>
>
> Ugh. This is starting to look like copy_process(). Any reason you
> couldn't move the bean counter bits to copy_process() instead?
This is more logical place since we _will_ charge task here
(next patchset for numproc).
It is logically better to charge objects in places where
they are allocated. At the same time we inherit tasks ubs here.

>> }
>>
>> #ifdef CONFIG_MMU
>>--- ./kernel/ub/Makefile.ubcore 2006-08-03 16:24:56.000000000 +0400
>>+++ ./kernel/ub/Makefile 2006-08-01 11:08:39.000000000 +0400
>>@@ -5,3 +5,4 @@
>> #
>>
>> obj-$(CONFIG_USER_RESOURCE) += beancounter.o
>>+obj-$(CONFIG_USER_RESOURCE) += misc.o
>>--- ./kernel/ub/beancounter.c.ubcore 2006-07-28 13:07:44.000000000 +0400
>>+++ ./kernel/ub/beancounter.c 2006-08-03 16:14:17.000000000 +0400
>>@@ -395,6 +395,10 @@
>> spin_lock_init(&ub_hash_lock);
>> slot = &ub_hash[ub_hash_fun(ub->ub_uid)];
>> hlist_add_head(&ub->hash, slot);
>>+
>>+ current->task_bc.exec_ub = ub;
>>+ current->task_bc.task_ub = get_beancounter(ub);
>>+ current->task_bc.fork_sub = get_beancounter(ub);
>> }
>>
>> void __init ub_init_late(void)
>>--- ./kernel/ub/misc.c.ubfork 2006-07-31 16:23:44.000000000 +0400
>>+++ ./kernel/ub/misc.c 2006-07-31 16:28:47.000000000 +0400
>>@@ -0,0 +1,34 @@
>>+/*
>>+ * kernel/ub/misc.c
>>+ *
>>+ * Copyright (C) 2006 OpenVZ. SWsoft Inc.
>>+ *
>>+ */
>>+
>>+#include <linux/sched.h>
>>+
>>+#include <ub/beancounter.h>
>>+#include <ub/task.h>
>>+
>>+int ub_task_charge(struct task_struct *parent, struct task_struct *new)
>>+{
>
>
> parent could be derived from new if you move the charge to copy_process
> instead of dup_task_struct.
we can split it into:
ub_charge_task() in dup_task_struct to account _task_ itself.
ub_copy_process() in copy_process() to inherit and initialize
exec_ub and fork_sub

what do you think?

>>+ struct task_beancounter *old_bc;
>>+ struct task_beancounter *new_bc;
>>+ struct user_beancounter *ub;
>>+
>>+ old_bc = &parent->task_bc;
>>+ new_bc = &new->task_bc;
>>+
>>+ ub = old_bc->fork_sub;
>>+ new_bc->exec_ub = get_beancounter(ub);
>>+ new_bc->task_ub = get_beancounter(ub);
>>+ new_bc->fork_sub = get_beancounter(ub);
>>+ return 0;
>>+}
>>+
>>+void ub_task_uncharge(struct task_struct *tsk)
>>+{
>>+ put_beancounter(tsk->task_bc.exec_ub);
>>+ put_beancounter(tsk->task_bc.task_ub);
>>+ put_beancounter(tsk->task_bc.fork_sub);
>>+}
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