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From: Dennis Zhou <dennisz@fb.com>
To: Tejun Heo <tj@kernel.org>
Cc: Christoph Lameter <cl@linux.com>,
	kernel-team@fb.com, linux-kernel@vger.kernel.org,
	linux-mm@kvack.org, Dennis Zhou <dennisszhou@gmail.com>
Subject: Re: [PATCH 05/10] percpu: change reserved_size to end page aligned
Date: Mon, 24 Jul 2017 16:04:47 -0400	[thread overview]
Message-ID: <20170724200446.GA91613@dennisz-mbp.dhcp.thefacebook.com> (raw)
In-Reply-To: <20170717164650.GJ3519177@devbig577.frc2.facebook.com>

Hi Tejun,

On Mon, Jul 17, 2017 at 12:46:50PM -0400, Tejun Heo wrote:
 
> Heh, that was pretty difficult to parse, but here's my question.  So,
> we're expanding reserved area so that its end aligns to page boundary
> which is completely fine.  We may end up with reserved area which is a
> bit larger than specified but no big deal.  However, we can't do the
> same thing with the boundary between the static and reserved chunks,
> so instead we pull down the start of the reserved area and mark off
> the overwrapping area, which is fine too.
> 
> My question is why we're doing one thing for the end of reserved area
> while we need to do a different thing for the beginning of it.  Can't
> we do the same thing in both cases?  ie. for the both boundaries
> between static and reserved, and reserved and dynamic, pull down the
> start to the page boundary and mark the overlapping areas used?

I've refactored the code to maintain start and end offsets. This removes
the need to expand the reserved region. There are a few more constraints
though. The reserved region must be a multiple of the minimum allocation
size. The static region and dynamic region are expanded and shrunk
respectively to maintain alignment with the minimum allocation size.

Thanks,
Dennis

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  parent reply	other threads:[~2017-07-24 20:05 UTC|newest]

Thread overview: 37+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-07-16  2:23 [PATCH 00/10] percpu: replace percpu area map allocator with bitmap allocator Dennis Zhou
2017-07-16  2:23 ` [PATCH 01/10] percpu: pcpu-stats change void buffer to int buffer Dennis Zhou
2017-07-17 14:44   ` Tejun Heo
2017-07-16  2:23 ` [PATCH 02/10] percpu: change the format for percpu_stats output Dennis Zhou
2017-07-17 14:46   ` Tejun Heo
2017-07-16  2:23 ` [PATCH 03/10] percpu: expose pcpu_nr_empty_pop_pages in pcpu_stats Dennis Zhou
2017-07-17 14:47   ` Tejun Heo
2017-07-16  2:23 ` [PATCH 04/10] percpu: update the header comment and pcpu_build_alloc_info comments Dennis Zhou
2017-07-17 14:53   ` Tejun Heo
2017-07-16  2:23 ` [PATCH 05/10] percpu: change reserved_size to end page aligned Dennis Zhou
2017-07-16  4:01   ` kbuild test robot
2017-07-16  5:11   ` kbuild test robot
2017-07-17 16:46   ` Tejun Heo
2017-07-17 19:10     ` Dennis Zhou
2017-07-24 20:04     ` Dennis Zhou [this message]
2017-07-16  2:23 ` [PATCH 06/10] percpu: modify base_addr to be region specific Dennis Zhou
2017-07-17 18:57   ` Tejun Heo
2017-07-18 19:26   ` Josef Bacik
2017-07-18 19:36     ` Matthew Wilcox
2017-07-19 14:20       ` Josef Bacik
2017-07-16  2:23 ` [PATCH 07/10] percpu: fix misnomer in schunk/dchunk variable names Dennis Zhou
2017-07-17 19:10   ` Tejun Heo
2017-07-24 20:07     ` Dennis Zhou
2017-07-16  2:23 ` [PATCH 08/10] percpu: change the number of pages marked in the first_chunk bitmaps Dennis Zhou
2017-07-17 19:26   ` Tejun Heo
2017-07-24 20:13     ` Dennis Zhou
2017-07-16  2:23 ` [PATCH 09/10] percpu: replace area map allocator with bitmap allocator Dennis Zhou
2017-07-17 23:27   ` Tejun Heo
2017-07-24 21:37     ` Dennis Zhou
2017-07-19 19:11   ` Josef Bacik
2017-07-19 22:19     ` Dennis Zhou
2017-07-19 19:16   ` Josef Bacik
2017-07-19 22:13     ` Dennis Zhou
2017-07-16  2:23 ` [PATCH 10/10] percpu: add optimizations on allocation path for the " Dennis Zhou
2017-07-17 23:32   ` Tejun Heo
2017-07-18 19:15 ` [PATCH 00/10] percpu: replace percpu area map allocator with " Josef Bacik
2017-07-24 21:14   ` Dennis Zhou

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