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To: Andrew Morton <akpm@osdl.org>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, hch@infradead.org
Subject: Re: [RFC] per thread page reservation patch
References: <20050103011113.6f6c8f44.akpm@osdl.org>
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From: Nikita Danilov <nikita@clusterfs.com>
Date: Fri, 07 Jan 2005 23:21:19 +0300
In-Reply-To: <20050107104838.0eacd301.akpm@osdl.org> (Andrew Morton's
 message of "Fri, 7 Jan 2005 10:48:38 -0800")
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Andrew Morton <akpm@osdl.org> writes:

> Vladimir Saveliev <vs@namesys.com> wrote:
>>
>> +int perthread_pages_reserve(int nrpages, int gfp)
>>  +{
>>  +	int i;
>>  +	struct list_head  accumulator;
>>  +	struct list_head *per_thread;
>>  +
>>  +	per_thread = get_per_thread_pages();
>>  +	INIT_LIST_HEAD(&accumulator);
>>  +	list_splice_init(per_thread, &accumulator);
>>  +	for (i = 0; i < nrpages; ++i) {
>
> This will end up reserving more pages than were asked for, if
> current->private_pages_count is non-zero.  Deliberate?

Yes. This is to make modular usage possible, so that


        perthread_pages_reserve(nrpages, gfp_mask);

        /* call some other code... */

        perthread_pages_release(unused_pages);

works correctly if "some other code" does per-thread reservations
too.

Nikita.