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.
WARNING: multiple messages have this Message-ID (diff)
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.
next prev parent reply other threads:[~2020-05-04 20:16 UTC|newest]
Thread overview: 82+ 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
2020-05-01 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 19:37 ` Joel Fernandes
2020-05-04 19:51 ` Uladzislau Rezki
2020-05-04 20:15 ` joel [this message]
2020-05-04 20:15 ` joel
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)
2020-04-29 5:11 ` kbuild test robot
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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