linux-kernel - Re: [PATCH v2 02/23] percpu: introduce start_offset to pcpu

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Message-ID: <20170725180417.GB18880@destiny>
Date:   Tue, 25 Jul 2017 14:04:18 -0400
From:   Josef Bacik <josef@...icpanda.com>
To:     Dennis Zhou <dennisz@...com>
Cc:     Tejun Heo <tj@...nel.org>, Christoph Lameter <cl@...ux.com>,
        Josef Bacik <josef@...icpanda.com>,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        kernel-team@...com, Dennis Zhou <dennisszhou@...il.com>
Subject: Re: [PATCH v2 02/23] percpu: introduce start_offset to pcpu_chunk

On Mon, Jul 24, 2017 at 07:01:59PM -0400, Dennis Zhou wrote:
> From: "Dennis Zhou (Facebook)" <dennisszhou@...il.com>
> 
> The reserved chunk arithmetic uses a global variable
> pcpu_reserved_chunk_limit that is set in the first chunk init code to
> hide a portion of the area map. The bitmap allocator to come will
> eventually move the base_addr up and require both the reserved chunk
> and static chunk to maintain this offset. pcpu_reserved_chunk_limit is
> removed and start_offset is added.
> 
> The first chunk that is circulated and is pcpu_first_chunk serves the
> dynamic region, the region following the reserved region. The reserved
> chunk address check will temporarily use the first chunk to identify its
> address range. A following patch will increase the base_addr and remove
> this. If there is no reserved chunk, this will check the static region
> and return false because those values should never be passed into the
> allocator.
> 
> Lastly, when linking in the first chunk, make sure to count the right
> free region for the number of empty populated pages.
> 
> Signed-off-by: Dennis Zhou <dennisszhou@...il.com>

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

Thanks,

Josef