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Date: Tue, 25 Jul 2017 15:20:57 -0400
From: Josef Bacik <josef@toxicpanda.com>
To: Dennis Zhou <dennisz@fb.com>
Cc: Tejun Heo <tj@kernel.org>, Christoph Lameter <cl@linux.com>,
        Josef Bacik <josef@toxicpanda.com>, linux-kernel@vger.kernel.org,
        linux-mm@kvack.org, kernel-team@fb.com,
        Dennis Zhou <dennisszhou@gmail.com>
Subject: Re: [PATCH v2 15/23] percpu: introduce bitmap metadata blocks
Message-ID: <20170725192057.GO18880@destiny>
References: <20170724230220.21774-1-dennisz@fb.com>
 <20170724230220.21774-16-dennisz@fb.com>
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On Mon, Jul 24, 2017 at 07:02:12PM -0400, Dennis Zhou wrote:
> From: "Dennis Zhou (Facebook)" <dennisszhou@gmail.com>
> 
> This patch introduces the bitmap metadata blocks and adds the skeleton
> of the code that will be used to maintain these blocks.  Each chunk's
> bitmap is made up of full metadata blocks. These blocks maintain basic
> metadata to help prevent scanning unnecssarily to update hints. Full
> scanning methods are used for the skeleton and will be replaced in the
> coming patches. A number of helper functions are added as well to do
> conversion of pages to blocks and manage offsets. Comments will be
> updated as the final version of each function is added.
> 
> There exists a relationship between PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE,
> the region size, and unit_size. Every chunk's region (including offsets)
> is page aligned at the beginning to preserve alignment. The end is
> aligned to LCM(PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE) to ensure that the end
> can fit with the populated page map which is by page and every metadata
> block is fully accounted for. The unit_size is already page aligned, but
> must also be aligned with PCPU_BITMAP_BLOCK_SIZE to ensure full metadata
> blocks.
> 
> Signed-off-by: Dennis Zhou <dennisszhou@gmail.com>

Reviewed-by: Josef Bacik <jbacik@fb.com>

Thanks,

Josef