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From: Tejun Heo <tj@kernel.org>
To: Vladimir Davydov <vdavydov@tarantool.org>
Cc: cl@linux.com, penberg@kernel.org, rientjes@google.com,
	iamjoonsoo.kim@lge.com, akpm@linux-foundation.org, jsvana@fb.com,
	hannes@cmpxchg.org, linux-kernel@vger.kernel.org,
	linux-mm@kvack.org, cgroups@vger.kernel.org, kernel-team@fb.com
Subject: Re: [PATCH 3/9] slab: simplify shutdown_memcg_caches()
Date: Sat, 14 Jan 2017 10:53:43 -0500	[thread overview]
Message-ID: <20170114155343.GA13589@mtj.duckdns.org> (raw)
In-Reply-To: <20170114153801.GB32693@mtj.duckdns.org>

On Sat, Jan 14, 2017 at 10:38:01AM -0500, Tejun Heo wrote:
> On Sat, Jan 14, 2017 at 04:27:22PM +0300, Vladimir Davydov wrote:
> > > -	 * Second, shutdown all caches left from memory cgroups that are now
> > > -	 * offline.
> > > +	 * Shutdown all caches.
> > >  	 */
> > >  	list_for_each_entry_safe(c, c2, &s->memcg_params.list,
> > >  				 memcg_params.list)
> > >  		shutdown_cache(c);
> > 
> > The point of this complexity was to leave caches that happen to have
> > objects when kmem_cache_destroy() is called on the list, so that they
> > could be reused later. This behavior was inherited from the global
> 
> Ah, right, I misread the branch.  I don't quite get how the cache can
> be reused later tho?  This is called when the memcg gets released and
> a clear error condition - the caller, kmem_cache_destroy(), handles it
> as an error condition too.

I think I understand it now.  This is the alias being able to find and
reuse the cache.  Heh, that's a weird optimization for a corner error
case.  Anyways, I'll drop this patch.

Thanks.

-- 
tejun

WARNING: multiple messages have this Message-ID (diff)
From: Tejun Heo <tj@kernel.org>
To: Vladimir Davydov <vdavydov@tarantool.org>
Cc: cl@linux.com, penberg@kernel.org, rientjes@google.com,
	iamjoonsoo.kim@lge.com, akpm@linux-foundation.org, jsvana@fb.com,
	hannes@cmpxchg.org, linux-kernel@vger.kernel.org,
	linux-mm@kvack.org, cgroups@vger.kernel.org, kernel-team@fb.com
Subject: Re: [PATCH 3/9] slab: simplify shutdown_memcg_caches()
Date: Sat, 14 Jan 2017 10:53:43 -0500	[thread overview]
Message-ID: <20170114155343.GA13589@mtj.duckdns.org> (raw)
In-Reply-To: <20170114153801.GB32693@mtj.duckdns.org>

On Sat, Jan 14, 2017 at 10:38:01AM -0500, Tejun Heo wrote:
> On Sat, Jan 14, 2017 at 04:27:22PM +0300, Vladimir Davydov wrote:
> > > -	 * Second, shutdown all caches left from memory cgroups that are now
> > > -	 * offline.
> > > +	 * Shutdown all caches.
> > >  	 */
> > >  	list_for_each_entry_safe(c, c2, &s->memcg_params.list,
> > >  				 memcg_params.list)
> > >  		shutdown_cache(c);
> > 
> > The point of this complexity was to leave caches that happen to have
> > objects when kmem_cache_destroy() is called on the list, so that they
> > could be reused later. This behavior was inherited from the global
> 
> Ah, right, I misread the branch.  I don't quite get how the cache can
> be reused later tho?  This is called when the memcg gets released and
> a clear error condition - the caller, kmem_cache_destroy(), handles it
> as an error condition too.

I think I understand it now.  This is the alias being able to find and
reuse the cache.  Heh, that's a weird optimization for a corner error
case.  Anyways, I'll drop this patch.

Thanks.

-- 
tejun

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  reply	other threads:[~2017-01-14 15:54 UTC|newest]

Thread overview: 56+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-01-14  5:54 [PATCHSET] slab: make memcg slab destruction scalable Tejun Heo
2017-01-14  5:54 ` Tejun Heo
2017-01-14  5:54 ` Tejun Heo
2017-01-14  5:54 ` [PATCH 1/9] Revert "slub: move synchronize_sched out of slab_mutex on shrink" Tejun Heo
2017-01-14  5:54   ` Tejun Heo
2017-01-14  5:54 ` [PATCH 2/9] slab: remove synchronous rcu_barrier() call in memcg cache release path Tejun Heo
2017-01-14  5:54   ` Tejun Heo
2017-01-14 13:19   ` Vladimir Davydov
2017-01-14 13:19     ` Vladimir Davydov
2017-01-14 15:19     ` Tejun Heo
2017-01-14 15:19       ` Tejun Heo
2017-01-17  0:07       ` Joonsoo Kim
2017-01-17  0:07         ` Joonsoo Kim
2017-01-17  0:07         ` Joonsoo Kim
2017-01-17 16:37         ` Tejun Heo
2017-01-17 16:37           ` Tejun Heo
2017-01-17 17:02           ` Tejun Heo
2017-01-17 17:02             ` Tejun Heo
2017-01-14  5:54 ` [PATCH 3/9] slab: simplify shutdown_memcg_caches() Tejun Heo
2017-01-14  5:54   ` Tejun Heo
2017-01-14 13:27   ` Vladimir Davydov
2017-01-14 13:27     ` Vladimir Davydov
2017-01-14 15:38     ` Tejun Heo
2017-01-14 15:38       ` Tejun Heo
2017-01-14 15:53       ` Tejun Heo [this message]
2017-01-14 15:53         ` Tejun Heo
2017-01-14  5:54 ` [PATCH 4/9] slab: reorganize memcg_cache_params Tejun Heo
2017-01-14  5:54   ` Tejun Heo
2017-01-14 13:30   ` Vladimir Davydov
2017-01-14 13:30     ` Vladimir Davydov
2017-01-14  5:54 ` [PATCH 5/9] slab: link memcg kmem_caches on their associated memory cgroup Tejun Heo
2017-01-14  5:54   ` Tejun Heo
2017-01-14 13:33   ` Vladimir Davydov
2017-01-14 13:33     ` Vladimir Davydov
2017-01-14  5:54 ` [PATCH 6/9] slab: don't put memcg caches on slab_caches list Tejun Heo
2017-01-14  5:54   ` Tejun Heo
2017-01-14 13:39   ` Vladimir Davydov
2017-01-14 13:39     ` Vladimir Davydov
2017-01-14 15:39     ` Tejun Heo
2017-01-14 15:39       ` Tejun Heo
2017-01-14 15:39       ` Tejun Heo
2017-01-14  5:54 ` [PATCH 7/9] slab: introduce __kmemcg_cache_deactivate() Tejun Heo
2017-01-14  5:54   ` Tejun Heo
2017-01-14 13:42   ` Vladimir Davydov
2017-01-14 13:42     ` Vladimir Davydov
2017-01-14 15:39     ` Tejun Heo
2017-01-14 15:39       ` Tejun Heo
2017-01-14  5:54 ` [PATCH 8/9] slab: remove synchronous synchronize_sched() from memcg cache deactivation path Tejun Heo
2017-01-14  5:54   ` Tejun Heo
2017-01-14 13:57   ` Vladimir Davydov
2017-01-14 13:57     ` Vladimir Davydov
2017-01-14 13:57     ` Vladimir Davydov
2017-01-14  5:54 ` [PATCH 9/9] slab: remove slub sysfs interface files early for empty memcg caches Tejun Heo
2017-01-14  5:54   ` Tejun Heo
2017-01-14 14:00   ` Vladimir Davydov
2017-01-14 14:00     ` Vladimir Davydov

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