From: Dennis Zhou <firstname.lastname@example.org>
To: Tejun Heo <email@example.com>
Cc: Christoph Lameter <firstname.lastname@example.org>,
email@example.com, Dennis Zhou <firstname.lastname@example.org>
Subject: Re: [PATCH 08/10] percpu: change the number of pages marked in the first_chunk bitmaps
Date: Mon, 24 Jul 2017 16:13:42 -0400 [thread overview]
Message-ID: <20170724201341.GC91613@dennisz-mbp.dhcp.thefacebook.com> (raw)
On Mon, Jul 17, 2017 at 03:26:02PM -0400, Tejun Heo wrote:
> > This patch changes the allocator to only mark allocated pages for the
> > region the population bitmap is used for. Prior, the bitmap was marked
> > completely used as the first chunk was allocated and immutable. This is
> > misleading because the first chunk may not be completely filled.
> > Additionally, with moving the base_addr up in the previous patch, the
> > population map no longer corresponds to what is being checked.
> This in isolation makes sense although the rationale isn't clear from
> the description. Is it a mere cleanup or is this needed to enable
> further changes?
This change is clean up to make sure there is no misunderstanding
between what part of the bitmap actually is meaningful and the actual
size of the bitmap.
> > pcpu_nr_empty_pop_pages is used to ensure there are a handful of free
> > pages around to serve atomic allocations. A new field, nr_empty_pop_pages,
> > is added to the pcpu_chunk struct to keep track of the number of empty
> > pages. This field is needed as the number of empty populated pages is
> > globally kept track of and deltas are used to update it. This new field
> > is exposed in percpu_stats.
> But I can't see why this is being added or why this is in the same
> patch with the previous change.
I've split this out into another patch.
> > Now that chunk->nr_pages is the number of pages the chunk is serving, it
> > is nice to use this in the work function for population and freeing of
> > chunks rather than use the global variable pcpu_unit_pages.
> The same goes for the above part. It's fine to collect misc changes
> into a patch when they're trivial and related in some ways but the
> content of this patch seems a bit random.
This change is needed in the same patch because chunk->nr_populated no
longer is set to pcpu_unit_pages. The checks would check the dynamic
chunk and then try to populate. Those checks should be checking against
the size of the region being served which is nr_pages.
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next prev parent reply other threads:[~2017-07-24 20:13 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
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 [this message]
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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