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From: Kirill Tkhai <ktkhai@virtuozzo.com>
To: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>,
	willy@infradead.org, wei.w.wang@intel.com
Cc: akpm@linux-foundation.org, vdavydov.dev@gmail.com,
	shakeelb@google.com, viro@zeniv.linux.org.uk, hannes@cmpxchg.org,
	mhocko@kernel.org, tglx@linutronix.de, pombredanne@nexb.com,
	stummala@codeaurora.org, gregkh@linuxfoundation.org,
	sfr@canb.auug.org.au, guro@fb.com, mka@chromium.org,
	chris@chris-wilson.co.uk, longman@redhat.com, minchan@kernel.org,
	hillf.zj@alibaba-inc.com, ying.huang@intel.com,
	mgorman@techsingularity.net, jbacik@fb.com, linux@roeck-us.net,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	lirongqing@baidu.com, aryabinin@virtuozzo.com
Subject: Re: [PATCH v2 01/12] mm: Assign id to every memcg-aware shrinker
Date: Wed, 18 Apr 2018 18:02:26 +0300	[thread overview]
Message-ID: <3a9fe2e8-284a-3d0a-8e75-617e9803e02c@virtuozzo.com> (raw)
In-Reply-To: <201804182332.FAC65178.FLVJFMSOtHOFQO@I-love.SAKURA.ne.jp>

On 18.04.2018 17:32, Tetsuo Handa wrote:
> Kirill Tkhai wrote:
>> On 18.04.2018 17:14, Tetsuo Handa wrote:
>>> Kirill Tkhai wrote:
>>>> The patch introduces shrinker::id number, which is used to enumerate
>>>> memcg-aware shrinkers. The number start from 0, and the code tries
>>>> to maintain it as small as possible.
>>>>
>>>> This will be used as to represent a memcg-aware shrinkers in memcg
>>>> shrinkers map.
>>>
>>> I'm not reading this thread. But is there reason "id" needs to be managed
>>> using smallest numbers? Can't we use address of shrinker object as "id"
>>> (which will be sparse bitmap, and would be managed using linked list for now)?
>>
>> Yes, it's needed to have the smallest numbers, as next patches introduce
>> per-memcg bitmap containing ids of shrinkers.
> 
> If you use sparse bitmap (xbitmap ?), I think you can do it.

There is no implementation in kernel, and search gave me this link:
https://patchwork.kernel.org/patch/10128397/

The problem is that it may allocate memory, and hence to fail.
While adding an element to shrinker lists (and setting a bit
in bitmap) mustn't fail. So, it's not possible to use sparse bitmap.

Kirill

  reply	other threads:[~2018-04-18 15:02 UTC|newest]

Thread overview: 37+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-17 18:52 [PATCH v2 00/12] Improve shrink_slab() scalability (old complexity was O(n^2), new is O(n)) Kirill Tkhai
2018-04-17 18:53 ` [PATCH v2 01/12] mm: Assign id to every memcg-aware shrinker Kirill Tkhai
2018-04-18 14:14   ` Tetsuo Handa
2018-04-18 14:27     ` Kirill Tkhai
2018-04-18 14:32       ` Tetsuo Handa
2018-04-18 15:02         ` Kirill Tkhai [this message]
2018-04-22 17:16   ` Vladimir Davydov
2018-04-17 18:53 ` [PATCH v2 02/12] memcg: Refactoring in mem_cgroup_alloc() Kirill Tkhai
2018-04-17 18:53 ` [PATCH v2 03/12] memcg: Refactoring in alloc_mem_cgroup_per_node_info() Kirill Tkhai
2018-04-17 18:53 ` [PATCH v2 04/12] mm: Assign memcg-aware shrinkers bitmap to memcg Kirill Tkhai
2018-04-18 12:55   ` kbuild test robot
2018-04-18 13:05     ` Kirill Tkhai
2018-04-22 17:59   ` Vladimir Davydov
2018-04-23 10:54     ` Kirill Tkhai
2018-04-24 11:28       ` Vladimir Davydov
2018-04-24 11:38         ` Kirill Tkhai
2018-04-24 12:15           ` Vladimir Davydov
2018-04-24 12:24             ` Kirill Tkhai
2018-04-28 15:08               ` Vladimir Davydov
2018-05-03 11:15                 ` Kirill Tkhai
2018-04-24 12:13         ` Kirill Tkhai
2018-04-23 11:02     ` Kirill Tkhai
2018-04-23 11:06     ` Kirill Tkhai
2018-04-24 11:08       ` Vladimir Davydov
2018-04-17 18:53 ` [PATCH v2 05/12] fs: Propagate shrinker::id to list_lru Kirill Tkhai
2018-04-22 18:03   ` Vladimir Davydov
2018-04-17 18:53 ` [PATCH v2 06/12] list_lru: Add memcg argument to list_lru_from_kmem() Kirill Tkhai
2018-04-17 18:54 ` [PATCH v2 07/12] list_lru: Pass dst_memcg argument to memcg_drain_list_lru_node() Kirill Tkhai
2018-04-17 18:54 ` [PATCH v2 08/12] list_lru: Pass lru " Kirill Tkhai
2018-04-17 18:54 ` [PATCH v2 09/12] mm: Set bit in memcg shrinker bitmap on first list_lru item apearance Kirill Tkhai
2018-04-17 18:54 ` [PATCH v2 10/12] mm: Iterate only over charged shrinkers during memcg shrink_slab() Kirill Tkhai
2018-04-22 18:19   ` Vladimir Davydov
2018-04-17 18:54 ` [PATCH v2 11/12] mm: Add SHRINK_EMPTY shrinker methods return value Kirill Tkhai
2018-04-17 18:54 ` [PATCH v2 12/12] mm: Clear shrinker bit if there are no objects related to memcg Kirill Tkhai
2018-04-22 18:21   ` Vladimir Davydov
2018-04-23 10:01     ` Kirill Tkhai
2018-04-24 10:56       ` Vladimir Davydov

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