Re: [PATCH md-6.12 00/41] md/md-bitmap: introduce bitmap_operations and make structure internel

[Yu Kuai <yukuai1@huaweicloud.com>]

Hi,

在 2024/08/22 16:38, Xiao Ni 写道:
> On Thu, Aug 22, 2024 at 10:52 AM Yu Kuai <yukuai1@huaweicloud.com> wrote:
>>
>> From: Yu Kuai <yukuai3@huawei.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.

Not yet, again because there are not much functional changes. I can run
lvm2 test later.

> 
> 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.

Of course there will be context conflict. After someone is applied, the
other one must rebase.

Thanks,
Kuai

> 
> 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
>>
> 
> 
> 
> .
>