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From: joel@joelfernandes.org
To: Uladzislau Rezki <urezki@gmail.com>,
	"Paul E. McKenney" <paulmck@kernel.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
	linux-mm <linux-mm@kvack.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	"Theodore Y . Ts'o" <tytso@mit.edu>,
	Matthew Wilcox <willy@infradead.org>, RCU <rcu@vger.kernel.org>,
	Oleksiy Avramchenko <oleksiy.avramchenko@sonymobile.com>
Subject: Re: [PATCH 09/24] rcu/tree: cache specified number of objects
Date: Mon, 04 May 2020 16:15:55 -0400	[thread overview]
Message-ID: <2A623E6F-878C-4C1F-9045-56710DE7851B@joelfernandes.org> (raw)
In-Reply-To: <20200504195128.GA21830@pc636>



On May 4, 2020 3:51:28 PM EDT, Uladzislau Rezki <urezki@gmail.com> wrote:
>> > > Since we don't care about traversing backwards, isn't it better
>to use llist
>> > > for this usecase?
>> > >
>> > > I think Vlad is using locking as we're also tracking the size of
>the llist to
>> > > know when to free pages. This tracking could suffer from the
>lost-update
>> > > problem without any locking, 2 lockless llist_add happened
>simulatenously.
>> > >
>> > > Also if list_head is used, it will take more space and still use
>locking.
>> >
>> > Indeed, it would be best to use a non-concurrent singly linked
>list.
>> 
>> Ok cool :-)
>> 
>> Is it safe to say something like the following is ruled out? ;-) :-D
>> #define kfree_rcu_list_add llist_add
>> 
>In that case i think it is better just to add a comment about using
>llist_head. To state that it used as a singular list to save space
>and the access is synchronized by the lock :)
>
>IMHO.

Sounds good to me. thanks,

 - Joel

>
>--
>Vlad Rezki

-- 
Sent from my Android device with K-9 Mail. Please excuse my brevity.

  reply	other threads:[~2020-05-04 20:16 UTC|newest]

Thread overview: 78+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-28 20:58 [PATCH 00/24] Introduce kvfree_rcu(1 or 2 arguments) Uladzislau Rezki (Sony)
2020-04-28 20:58 ` [PATCH 01/24] rcu/tree: Keep kfree_rcu() awake during lock contention Uladzislau Rezki (Sony)
2020-04-28 20:58 ` [PATCH 02/24] rcu/tree: Skip entry into the page allocator for PREEMPT_RT Uladzislau Rezki (Sony)
2020-04-28 20:58 ` [PATCH 03/24] rcu/tree: Use consistent style for comments Uladzislau Rezki (Sony)
2020-05-01 19:05   ` Paul E. McKenney
2020-05-01 20:52     ` Joe Perches
2020-05-03 23:44       ` Joel Fernandes
2020-05-04  0:23         ` Paul E. McKenney
2020-05-04  0:34           ` Joe Perches
2020-05-04  0:41           ` Joel Fernandes
2020-05-03 23:52     ` Joel Fernandes
2020-05-04  0:26       ` Paul E. McKenney
2020-05-04  0:39         ` Joel Fernandes
2020-04-28 20:58 ` [PATCH 04/24] rcu/tree: Repeat the monitor if any free channel is busy Uladzislau Rezki (Sony)
2020-04-28 20:58 ` [PATCH 05/24] rcu/tree: Simplify debug_objects handling Uladzislau Rezki (Sony)
2020-04-28 20:58 ` [PATCH 06/24] rcu/tree: Simplify KFREE_BULK_MAX_ENTR macro Uladzislau Rezki (Sony)
2020-04-28 20:58 ` [PATCH 07/24] rcu/tree: move locking/unlocking to separate functions Uladzislau Rezki (Sony)
2020-04-28 20:58 ` [PATCH 08/24] rcu/tree: Use static initializer for krc.lock Uladzislau Rezki (Sony)
2020-05-01 21:17   ` Paul E. McKenney
2020-05-04 12:10     ` Uladzislau Rezki
2020-04-28 20:58 ` [PATCH 09/24] rcu/tree: cache specified number of objects Uladzislau Rezki (Sony)
2020-05-01 21:27   ` Paul E. McKenney
2020-05-04 12:43     ` Uladzislau Rezki
2020-05-04 15:24       ` Paul E. McKenney
2020-05-04 17:48         ` Uladzislau Rezki
2020-05-04 18:07           ` Paul E. McKenney
2020-05-04 18:08           ` Joel Fernandes
2020-05-04 19:01             ` Paul E. McKenney
2020-05-04 19:37               ` Joel Fernandes
2020-05-04 19:51                 ` Uladzislau Rezki
2020-05-04 20:15                   ` joel [this message]
2020-05-04 20:16                   ` Paul E. McKenney
2020-05-05 11:03                     ` Uladzislau Rezki
2020-04-28 20:58 ` [PATCH 10/24] rcu/tree: add rcutree.rcu_min_cached_objs description Uladzislau Rezki (Sony)
2020-05-01 22:25   ` Paul E. McKenney
2020-05-04 12:44     ` Uladzislau Rezki
2020-04-28 20:58 ` [PATCH 11/24] rcu/tree: Maintain separate array for vmalloc ptrs Uladzislau Rezki (Sony)
2020-05-01 21:37   ` Paul E. McKenney
2020-05-03 23:42     ` Joel Fernandes
2020-05-04  0:20       ` Paul E. McKenney
2020-05-04  0:58         ` Joel Fernandes
2020-05-04  2:20           ` Paul E. McKenney
2020-05-04 14:25     ` Uladzislau Rezki
2020-04-28 20:58 ` [PATCH 12/24] rcu/tiny: support vmalloc in tiny-RCU Uladzislau Rezki (Sony)
2020-04-28 20:58 ` [PATCH 13/24] rcu: Rename rcu_invoke_kfree_callback/rcu_kfree_callback Uladzislau Rezki (Sony)
2020-04-28 20:58 ` [PATCH 14/24] rcu: Rename __is_kfree_rcu_offset() macro Uladzislau Rezki (Sony)
2020-04-28 20:58 ` [PATCH 15/24] rcu: Rename kfree_call_rcu() to the kvfree_call_rcu() Uladzislau Rezki (Sony)
2020-04-28 20:58 ` [PATCH 16/24] mm/list_lru.c: Rename kvfree_rcu() to local variant Uladzislau Rezki (Sony)
2020-04-28 20:58 ` [PATCH 17/24] rcu: Introduce 2 arg kvfree_rcu() interface Uladzislau Rezki (Sony)
2020-04-28 20:58 ` [PATCH 18/24] mm/list_lru.c: Remove kvfree_rcu_local() function Uladzislau Rezki (Sony)
2020-04-28 20:58 ` [PATCH 19/24] rcu/tree: Support reclaim for head-less object Uladzislau Rezki (Sony)
2020-05-01 22:39   ` Paul E. McKenney
2020-05-04  0:12     ` Joel Fernandes
2020-05-04  0:28       ` Paul E. McKenney
2020-05-04  0:32         ` Joel Fernandes
2020-05-04 14:21           ` Uladzislau Rezki
2020-05-04 15:31             ` Paul E. McKenney
2020-05-04 16:56               ` Uladzislau Rezki
2020-05-04 17:08                 ` Paul E. McKenney
2020-05-04 12:57     ` Uladzislau Rezki
2020-04-28 20:58 ` [PATCH 20/24] rcu/tree: Make kvfree_rcu() tolerate any alignment Uladzislau Rezki (Sony)
2020-05-01 23:00   ` Paul E. McKenney
2020-05-04  0:24     ` Joel Fernandes
2020-05-04  0:29       ` Paul E. McKenney
2020-05-04  0:31         ` Joel Fernandes
2020-05-04 12:56           ` Uladzislau Rezki
2020-04-28 20:59 ` [PATCH 21/24] rcu/tiny: move kvfree_call_rcu() out of header Uladzislau Rezki (Sony)
2020-05-01 23:03   ` Paul E. McKenney
2020-05-04 12:45     ` Uladzislau Rezki
2020-05-06 18:29     ` Uladzislau Rezki
2020-05-06 18:45       ` Paul E. McKenney
2020-05-07 17:34         ` Uladzislau Rezki
2020-04-28 20:59 ` [PATCH 22/24] rcu/tiny: support reclaim for head-less object Uladzislau Rezki (Sony)
2020-05-01 23:06   ` Paul E. McKenney
2020-05-04  0:27     ` Joel Fernandes
2020-05-04 12:45       ` Uladzislau Rezki
2020-04-28 20:59 ` [PATCH 23/24] rcu: Introduce 1 arg kvfree_rcu() interface Uladzislau Rezki (Sony)
2020-04-28 20:59 ` [PATCH 24/24] lib/test_vmalloc.c: Add test cases for kvfree_rcu() Uladzislau Rezki (Sony)

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