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From: Zhi Wang <zhi.a.wang@intel.com>
To: Johannes Weiner <hannes@cmpxchg.org>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-mm@kvack.org" <linux-mm@kvack.org>,
	"akpm@linux-foundation.org" <akpm@linux-foundation.org>,
	Ingo Molnar <mingo@redhat.com>
Subject: Re: [PATCH] mm: mempool: Factor out mempool_refill()
Date: Wed, 16 Dec 2015 11:19:56 +0800	[thread overview]
Message-ID: <5670D85C.60106@intel.com> (raw)
In-Reply-To: <20151215212638.GA17162@cmpxchg.org>

Hi Johannes:
     Thanks for the reply. In the end of the mempool_resize(), it will 
call the mempool_refill() to do the rest of the work. So this is not one 
of the "no-caller" case. If you insist this is a "no-caller" case, 
perhaps I should change it to a "static" function without exposing a new 
interface?

Personally I think mempool_refill() should be one of the typical 
interfaces in an implementation of a mempool. Currently the mempool will 
not grow only if pool->min_nr > new_min_nr.

So when user wants to refill the mempool immediately, not resize a 
mempool, in the current implementation, it has to do 2x 
mempool_resize(). First one is mempool_resize(pool->min_nr - 1), second 
one is mempool_resize(new_min_nr). So the refill action would truly 
happen. This is ugly and not convenient.

On 12/16/15 05:26, Johannes Weiner wrote:
> On Mon, Dec 14, 2015 at 11:09:43AM +0000, Wang, Zhi A wrote:
>> This patch factors out mempool_refill() from mempool_resize(). It's reasonable
>> that the mempool user wants to refill the pool immdiately when it has chance
>> e.g. inside a sleepible context, so that next time in the IRQ context the pool
>> would have much more available elements to allocate.
>>
>> After the refactor, mempool_refill() can also executes with mempool_resize()
>> /mempool_alloc/mempool_free() or another mempool_refill().
>>
>> Signed-off-by: Zhi Wang <zhi.a.wang@intel.com>
>
> Who is going to call that function? Adding a new interace usually
> comes with a user, or as part of a series that adds users.
>

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  reply	other threads:[~2015-12-16  3:20 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <1449978390-10931-1-git-send-email-zhi.a.wang@intel.com>
2015-12-14 11:09 ` [PATCH] mm: mempool: Factor out mempool_refill() Wang, Zhi A
2015-12-15 21:26   ` Johannes Weiner
2015-12-16  3:19     ` Zhi Wang [this message]
2015-12-11  6:18 Zhi Wang

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