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Re: [PATCH 2/6] BC: beancounters core (API) [message #5606 is a reply to message #5568]

Thu, 24 August 2006 11:09

Oleg Nesterov
Messages: 143
Registered: August 2006

Senior Member

On 08/23, Andrew Morton wrote:
>
> On Wed, 23 Aug 2006 15:03:07 +0400
> Kirill Korotaev <dev@sw.ru> wrote:
>
> > +void __put_beancounter(struct beancounter *bc)
> > +{
> > + unsigned long flags;
> > +
> > + /* equivalent to atomic_dec_and_lock_irqsave() */
> > + local_irq_save(flags);
> > + if (likely(!atomic_dec_and_lock(&bc->bc_refcount, &bc_hash_lock))) {
> > + local_irq_restore(flags);
> > + if (unlikely(atomic_read(&bc->bc_refcount) < 0))
> > + printk(KERN_ERR "BC: Bad refcount: bc=%p, "
> > + "luid=%d, ref=%d\n",
> > + bc, bc->bc_id,
> > + atomic_read(&bc->bc_refcount));
> > + return;
> > + }
> > +
> > + BUG_ON(bc == &init_bc);
> > + verify_held(bc);
> > + hlist_del(&bc->hash);
> > + spin_unlock_irqrestore(&bc_hash_lock, flags);
> > + kmem_cache_free(bc_cachep, bc);
> > +}
>
> I wonder if it's safe and worthwhile to optimise away the local_irq_save():

Suppose ->bc_refcount == 1

> if (atomic_dec_and_test(&bc->bc_refcount)) {

Yes, preempted or blocks on spin_lock() below.

another cpu locks bc_hash_lock, does get_beancounter() (beancounter_findcreate),
then does put_beancounter(), and frees it.

> spin_lock_irqsave(&bc_hash_lock, flags);
> if (atomic_read(&bc->bc_refcount) == 0) {

Yes,

> free it
>

Already freed.

Oleg.

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[Message index]

		[PATCH] BC: resource beancounters (v2) By: dev on Wed, 23 August 2006 10:44
		[PATCH 1/6] BC: kconfig By: dev on Wed, 23 August 2006 10:59
		Re: [PATCH 1/6] BC: kconfig By: Alexey Dobriyan on Wed, 23 August 2006 13:04
		Re: [PATCH 1/6] BC: kconfig By: Dave Hansen on Wed, 23 August 2006 22:04
		Re: [PATCH 1/6] BC: kconfig By: Matt Helsley on Wed, 23 August 2006 22:13
		Re: [PATCH 1/6] BC: kconfig By: dev on Fri, 25 August 2006 11:27
		Re: [PATCH 1/6] BC: kconfig By: dev on Fri, 25 August 2006 11:31
		Re: [PATCH 1/6] BC: kconfig By: rdunlap on Wed, 23 August 2006 22:29
		Re: [PATCH 1/6] BC: kconfig By: Matt Helsley on Wed, 23 August 2006 22:27
		Re: [PATCH 1/6] BC: kconfig By: Chandra Seetharaman on Thu, 24 August 2006 00:23
		Re: [ckrm-tech] [PATCH 1/6] BC: kconfig By: dev on Thu, 24 August 2006 11:47
		Re: [ckrm-tech] [PATCH 1/6] BC: kconfig By: Matt Helsley on Thu, 24 August 2006 22:23
		[PATCH 2/6] BC: beancounters core (API) By: dev on Wed, 23 August 2006 11:00
		Re: [PATCH 2/6] BC: beancounters core (API) By: Andi Kleen on Wed, 23 August 2006 11:37
		Re: [PATCH 2/6] BC: beancounters core (API) By: dev on Wed, 23 August 2006 13:25
		Re: [PATCH 2/6] BC: beancounters core (API) By: Andi Kleen on Wed, 23 August 2006 13:48
		Re: [PATCH 2/6] BC: beancounters core (API) By: dev on Wed, 23 August 2006 13:46
		Re: [PATCH 2/6] BC: beancounters core (API) By: Alexey Dobriyan on Wed, 23 August 2006 13:53
		Re: [PATCH 2/6] BC: beancounters core (API) By: Matt Helsley on Wed, 23 August 2006 22:05
		Re: [PATCH 2/6] BC: beancounters core (API) By: Alexey Dobriyan on Wed, 23 August 2006 13:30
		Re: [PATCH 2/6] BC: beancounters core (API) By: Andrew Morton on Wed, 23 August 2006 16:42
		Re: [PATCH 2/6] BC: beancounters core (API) By: Oleg Nesterov on Thu, 24 August 2006 11:09
		Re: [PATCH 2/6] BC: beancounters core (API) By: dev on Thu, 24 August 2006 12:03
		Re: [PATCH 2/6] BC: beancounters core (API) By: Andrew Morton on Thu, 24 August 2006 15:00
		Re: [PATCH 2/6] BC: beancounters core (API) By: dev on Fri, 25 August 2006 10:51
		Re: [PATCH 2/6] BC: beancounters core (API) By: Oleg Nesterov on Thu, 24 August 2006 17:09
		[PATCH 3/6] BC: context inheriting and changing By: dev on Wed, 23 August 2006 11:02
		[PATCH 4/6] BC: user interface (syscalls) By: dev on Wed, 23 August 2006 11:03
		Re: [PATCH 4/6] BC: user interface (syscalls) By: dev on Wed, 23 August 2006 13:40
		Re: [PATCH 4/6] BC: user interface (syscalls) By: Andrew Morton on Wed, 23 August 2006 16:50
		Re: [PATCH 4/6] BC: user interface (syscalls) By: Alan Cox on Wed, 23 August 2006 17:08
		Re: [PATCH 4/6] BC: user interface (syscalls) By: Andrew Morton on Thu, 24 August 2006 04:35
		Re: [PATCH 4/6] BC: user interface (syscalls) By: Alan Cox on Thu, 24 August 2006 10:42
		Re: [PATCH 4/6] BC: user interface (syscalls) By: Alexey Dobriyan on Thu, 24 August 2006 13:08
		Re: [PATCH 4/6] BC: user interface (syscalls) By: dev on Fri, 25 August 2006 10:54
		Re: [PATCH 4/6] BC: user interface (syscalls) By: Alexey Dobriyan on Wed, 23 August 2006 13:41
		Re: [PATCH 4/6] BC: user interface (syscalls) By: Chandra Seetharaman on Thu, 24 August 2006 00:30
		[PATCH 5/6] BC: kernel memory accounting (core) By: dev on Wed, 23 August 2006 11:04
		Re: [PATCH 5/6] BC: kernel memory accounting (core) By: Chandra Seetharaman on Thu, 24 August 2006 00:36
		Re: [PATCH 5/6] BC: kernel memory accounting (core) By: Oleg Nesterov on Thu, 24 August 2006 16:59
		Re: [PATCH 5/6] BC: kernel memory accounting (core) By: dev on Fri, 25 August 2006 10:06
		[PATCH 6/6] BC: kernel memory accounting (marks) By: dev on Wed, 23 August 2006 11:05
		Re: [PATCH 6/6] BC: kernel memory accounting (marks) By: Dave Hansen on Wed, 23 August 2006 18:30
		Re: [PATCH 6/6] BC: kernel memory accounting (marks) By: dev on Tue, 29 August 2006 09:52
		Re: [PATCH 6/6] BC: kernel memory accounting (marks) By: Dave Hansen on Tue, 29 August 2006 15:48
		Re: [PATCH 6/6] BC: kernel memory accounting (marks) By: Dave Hansen on Wed, 23 August 2006 23:03
		Re: [PATCH 6/6] BC: kernel memory accounting (marks) By: Geert Uytterhoeven on Thu, 24 August 2006 09:30
		Re: [PATCH 6/6] BC: kernel memory accounting (marks) By: Dave Hansen on Thu, 24 August 2006 15:52
		Re: [PATCH 6/6] BC: kernel memory accounting (marks) By: dev on Tue, 29 August 2006 14:34
		Re: [PATCH 6/6] BC: kernel memory accounting (marks) By: dev on Tue, 29 August 2006 15:53
		Re: [PATCH] BC: resource beancounters (v2) By: Andrew Morton on Wed, 23 August 2006 17:05
		Re: [PATCH] BC: resource beancounters (v2) By: Chandra Seetharaman on Thu, 24 August 2006 00:17
		Re: [PATCH] BC: resource beancounters (v2) By: dev on Fri, 25 August 2006 11:47
		Re: [PATCH] BC: resource beancounters (v2) By: Andrew Morton on Fri, 25 August 2006 14:30
		Re: [PATCH] BC: resource beancounters (v2) By: Andi Kleen on Fri, 25 August 2006 14:48
		Re: [PATCH] BC: resource beancounters (v2) By: dev on Mon, 28 August 2006 08:27
		Re: [PATCH] BC: resource beancounters (v2) By: Nick Piggin on Fri, 25 August 2006 15:14
		Re: BC: resource beancounters (v2) By: Andrey Savochkin on Fri, 25 August 2006 16:30
		Re: BC: resource beancounters (v2) By: Andrew Morton on Fri, 25 August 2006 17:50
		Re: BC: resource beancounters (v2) By: Chandra Seetharaman on Fri, 25 August 2006 19:00
		Re: BC: resource beancounters (v2) By: Rohit Seth on Sat, 26 August 2006 02:15
		Re: BC: resource beancounters (v2) By: Alan Cox on Sat, 26 August 2006 16:16
		Re: BC: resource beancounters (v2) By: Rohit Seth on Mon, 28 August 2006 16:48
		Re: Re: BC: resource beancounters (v2) By: kir on Mon, 28 August 2006 17:40
		Re: Re: BC: resource beancounters (v2) By: Rohit Seth on Mon, 28 August 2006 22:28
		Re: Re: BC: resource beancounters (v2) By: Alan Cox on Tue, 29 August 2006 10:15
		Re: Re: BC: resource beancounters (v2) By: Rohit Seth on Tue, 29 August 2006 17:30
		Re: Re: BC: resource beancounters (v2) By: Alan Cox on Tue, 29 August 2006 18:46
		Re: Re: BC: resource beancounters (v2) By: Rohit Seth on Tue, 29 August 2006 19:15
		Re: [PATCH] BC: resource beancounters (v2) By: dev on Tue, 29 August 2006 15:33
		Re: [PATCH] BC: resource beancounters (v2) By: Balbir Singh on Tue, 29 August 2006 17:08
		Re: [PATCH] BC: resource beancounters (v2) By: Cedric Le Goater on Wed, 23 August 2006 21:00
		Re: [PATCH] BC: resource beancounters (v2) By: Jan Engelhardt on Thu, 24 August 2006 05:52
		Re: [PATCH] BC: resource beancounters (v2) By: Alan Cox on Thu, 24 August 2006 10:38
		Re: [PATCH] BC: resource beancounters (v2) By: Alan Cox on Fri, 25 August 2006 15:36
		Re: [PATCH] BC: resource beancounters (v2) By: Nick Piggin on Sat, 26 August 2006 03:55

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