linux-kernel - Re: [PATCH md-6.12 00/41] md/md-bitmap: introduce bitmap

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Message-ID: <CALTww28Pj6kPSc_JGX3ya6B5bgUUyoHxVXd6BnCZ1P-ub404bw@mail.gmail.com>
Date: Thu, 22 Aug 2024 16:38:42 +0800
From: Xiao Ni <xni@...hat.com>
To: Yu Kuai <yukuai1@...weicloud.com>
Cc: song@...nel.org, mariusz.tkaczyk@...ux.intel.com, l@...enly.org, 
	linux-kernel@...r.kernel.org, linux-raid@...r.kernel.org, yukuai3@...wei.com, 
	yi.zhang@...wei.com, yangerkun@...wei.com
Subject: Re: [PATCH md-6.12 00/41] md/md-bitmap: introduce bitmap_operations
 and make structure internel

On Thu, Aug 22, 2024 at 10:52 AM Yu Kuai <yukuai1@...weicloud.com> wrote:
>
> From: Yu Kuai <yukuai3@...wei.com>
>
> Changes from RFC v1:
>  - add patch 1-8 to prevent dereference bitmap directly, and the last
>  patch to make bitmap structure internel.
>  - use plain function alls "bitmap_ops->xxx()" directly;
>
> Changes from RFC v2:
>  - some coding style.
>
> The background is that currently bitmap is using a global spin_lock,
> cauing lock contention and huge IO performance degration for all raid
> levels.
>
> However, it's impossible to implement a new lock free bitmap with
> current situation that md-bitmap exposes the internal implementation
> with lots of exported apis. Hence bitmap_operations is invented, to
> describe bitmap core implementation, and a new bitmap can be introduced
> with a new bitmap_operations, we only need to switch to the new one
> during initialization.
>
> And with this we can build bitmap as kernel module, but that's not
> our concern for now.
>
> This version was tested with mdadm tests. There are still few failed
> tests in my VM, howerver, it's the test itself need to be fixed and
> we're working on it.

Hi Kuai

Do you run lvm2 test regression tests? It's better to run lvm2
regression tests for such a big change.

And by the way, does this patch set have a conflict with patch set
"[RFC V7] md/bitmap: Optimize lock contention". I haven't read the
patches, it's an optimization for the bitmap lock too.

Best Regards
Xiao
>
> Yu Kuai (41):
>   md/raid1: use md_bitmap_wait_behind_writes() in raid1_read_request()
>   md/md-bitmap: replace md_bitmap_status() with a new helper
>     md_bitmap_get_stats()
>   md: use new helper md_bitmap_get_stats() in update_array_info()
>   md/md-bitmap: add 'events_cleared' into struct md_bitmap_stats
>   md/md-bitmap: add 'sync_size' into struct md_bitmap_stats
>   md/md-bitmap: add 'file_pages' into struct md_bitmap_stats
>   md/md-bitmap: add 'behind_writes' and 'behind_wait' into struct
>     md_bitmap_stats
>   md/md-cluster: use helper md_bitmap_get_stats() to get pages in
>     resize_bitmaps()
>   md/md-bitmap: add a new helper md_bitmap_set_pages()
>   md/md-bitmap: introduce struct bitmap_operations
>   md/md-bitmap: simplify md_bitmap_create() + md_bitmap_load()
>   md/md-bitmap: merge md_bitmap_create() into bitmap_operations
>   md/md-bitmap: merge md_bitmap_load() into bitmap_operations
>   md/md-bitmap: merge md_bitmap_destroy() into bitmap_operations
>   md/md-bitmap: merge md_bitmap_flush() into bitmap_operations
>   md/md-bitmap: make md_bitmap_print_sb() internal
>   md/md-bitmap: merge md_bitmap_update_sb() into bitmap_operations
>   md/md-bitmap: merge md_bitmap_status() into bitmap_operations
>   md/md-bitmap: remove md_bitmap_setallbits()
>   md/md-bitmap: merge bitmap_write_all() into bitmap_operations
>   md/md-bitmap: merge md_bitmap_dirty_bits() into bitmap_operations
>   md/md-bitmap: merge md_bitmap_startwrite() into bitmap_operations
>   md/md-bitmap: merge md_bitmap_endwrite() into bitmap_operations
>   md/md-bitmap: merge md_bitmap_start_sync() into bitmap_operations
>   md/md-bitmap: remove the parameter 'aborted' for md_bitmap_end_sync()
>   md/md-bitmap: merge md_bitmap_end_sync() into bitmap_operations
>   md/md-bitmap: merge md_bitmap_close_sync() into bitmap_operations
>   md/md-bitmap: mrege md_bitmap_cond_end_sync() into bitmap_operations
>   md/md-bitmap: merge md_bitmap_sync_with_cluster() into
>     bitmap_operations
>   md/md-bitmap: merge md_bitmap_unplug_async() into md_bitmap_unplug()
>   md/md-bitmap: merge bitmap_unplug() into bitmap_operations
>   md/md-bitmap: merge md_bitmap_daemon_work() into bitmap_operations
>   md/md-bitmap: pass in mddev directly for md_bitmap_resize()
>   md/md-bitmap: merge md_bitmap_resize() into bitmap_operations
>   md/md-bitmap: merge get_bitmap_from_slot() into bitmap_operations
>   md/md-bitmap: merge md_bitmap_copy_from_slot() into struct
>     bitmap_operation.
>   md/md-bitmap: merge md_bitmap_set_pages() into struct
>     bitmap_operations
>   md/md-bitmap: merge md_bitmap_free() into bitmap_operations
>   md/md-bitmap: merge md_bitmap_wait_behind_writes() into
>     bitmap_operations
>   md/md-bitmap: merge md_bitmap_enabled() into bitmap_operations
>   md/md-bitmap: make in memory structure internal
>
>  drivers/md/dm-raid.c     |   7 +-
>  drivers/md/md-bitmap.c   | 560 +++++++++++++++++++++++++++++----------
>  drivers/md/md-bitmap.h   | 268 ++++---------------
>  drivers/md/md-cluster.c  |  91 ++++---
>  drivers/md/md.c          | 155 +++++++----
>  drivers/md/md.h          |   3 +-
>  drivers/md/raid1-10.c    |   9 +-
>  drivers/md/raid1.c       |  78 +++---
>  drivers/md/raid10.c      |  73 ++---
>  drivers/md/raid5-cache.c |   8 +-
>  drivers/md/raid5.c       |  62 ++---
>  11 files changed, 752 insertions(+), 562 deletions(-)
>
> --
> 2.39.2
>