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From: Qu Wenruo <quwenruo.btrfs@gmx.com>
To: Nikolay Borisov <nborisov@suse.com>, Qu Wenruo <wqu@suse.com>,
	linux-btrfs@vger.kernel.org
Subject: Re: [PATCH v2 03/19] btrfs: calculate inline extent buffer page size based on page size
Date: Tue, 15 Sep 2020 18:05:09 +0800	[thread overview]
Message-ID: <7e36f34f-2f16-a771-9a3e-9dcdae8db878@gmx.com> (raw)
In-Reply-To: <acd4c9ff-841e-1449-7253-222d5469967d@suse.com>



On 2020/9/15 下午4:35, Nikolay Borisov wrote:
>
>
> On 15.09.20 г. 8:35 ч., Qu Wenruo wrote:
>> Btrfs only support 64K as max node size, thus for 4K page system, we
>> would have at most 16 pages for one extent buffer.
>>
>> For a system using 64K page size, we would really have just one
>> single page.
>>
>> While we always use 16 pages for extent_buffer::pages[], this means for
>> systems using 64K pages, we are wasting memory for the 15 pages which
>> will never be utilized.
>>
>> So this patch will change how the extent_buffer::pages[] array size is
>> calclulated, now it will be calculated using
>> BTRFS_MAX_METADATA_BLOCKSIZE and PAGE_SIZE.
>>
>> For systems using 4K page size, it will stay 16 pages.
>> For systems using 64K page size, it will be just 1 page.
>>
>> Signed-off-by: Qu Wenruo <wqu@suse.com>
>
> Reviewed-by: Nikolay Borisov <nborisov@suse.com>
>
> <snip>
>
>> diff --git a/fs/btrfs/extent_io.h b/fs/btrfs/extent_io.h
>> index 00a88f2eb5ab..d511890702cc 100644
>> --- a/fs/btrfs/extent_io.h
>> +++ b/fs/btrfs/extent_io.h
>> @@ -85,9 +85,11 @@ struct extent_io_ops {
>>  				    int mirror);
>>  };
>>
>> -
>> -#define INLINE_EXTENT_BUFFER_PAGES 16
>> -#define MAX_INLINE_EXTENT_BUFFER_SIZE (INLINE_EXTENT_BUFFER_PAGES * PAGE_SIZE)
>> +/*
>> + * The SZ_64K is BTRFS_MAX_METADATA_BLOCKSIZE, here just to avoid circle
>> + * including "ctree.h".
>> + */
>> +#define INLINE_EXTENT_BUFFER_PAGES (SZ_64K / PAGE_SIZE)
>
> nit: Instead of doing this it would be better if this define is simply
> moved next to BTRFS_MAX_METADATA_BLOCKSIZE so that every define relating
> to eb's are clustered together.

It would be better to only define the macro in extent buffer context.

We have put too many things into ctree.h so that we hit such problem in
the first place.

Thanks,
Qu
>
>>  struct extent_buffer {
>>  	u64 start;
>>  	unsigned long len;
>>

  reply	other threads:[~2020-09-15 10:05 UTC|newest]

Thread overview: 58+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-15  5:35 [PATCH v2 00/19] btrfs: add read-only support for subpage sector size Qu Wenruo
2020-09-15  5:35 ` [PATCH v2 01/19] btrfs: extent-io-tests: remove invalid tests Qu Wenruo
2020-09-15  5:35 ` [PATCH v2 02/19] btrfs: remove the unnecessary parameter @start and @len for check_data_csum() Qu Wenruo
2020-09-15  8:39   ` Johannes Thumshirn
2020-09-15  5:35 ` [PATCH v2 03/19] btrfs: calculate inline extent buffer page size based on page size Qu Wenruo
2020-09-15  8:35   ` Nikolay Borisov
2020-09-15 10:05     ` Qu Wenruo [this message]
2020-09-15  8:40   ` Johannes Thumshirn
2020-09-15  5:35 ` [PATCH v2 04/19] btrfs: remove the open-code to read disk-key Qu Wenruo
2020-09-15  8:36   ` Nikolay Borisov
2020-09-15  8:40   ` Johannes Thumshirn
2020-09-16 16:01   ` David Sterba
2020-09-17  8:02     ` Qu Wenruo
2020-09-17 12:37       ` David Sterba
2020-09-17 13:15         ` Qu Wenruo
2020-09-17 22:41           ` David Sterba
2020-09-17 23:26             ` Qu Wenruo
2020-09-15  5:35 ` [PATCH v2 05/19] btrfs: make btrfs_fs_info::buffer_radix to take sector size devided values Qu Wenruo
2020-09-15  8:27   ` Johannes Thumshirn
2020-09-15 10:04     ` Qu Wenruo
2020-09-15 10:12       ` Johannes Thumshirn
2020-09-15 17:40   ` kernel test robot
2020-09-15  5:35 ` [PATCH v2 06/19] btrfs: don't allow tree block to cross page boundary for subpage support Qu Wenruo
2020-09-15  8:37   ` Nikolay Borisov
2020-09-15 10:06     ` Qu Wenruo
2020-09-15  8:44   ` Johannes Thumshirn
2020-09-15  5:35 ` [PATCH v2 07/19] btrfs: update num_extent_pages() to support subpage sized extent buffer Qu Wenruo
2020-09-15  8:42   ` Johannes Thumshirn
2020-09-15 10:07     ` Qu Wenruo
2020-09-15 10:12       ` Johannes Thumshirn
2020-09-15 10:07     ` Qu Wenruo
2020-09-15  5:35 ` [PATCH v2 08/19] btrfs: handle sectorsize < PAGE_SIZE case for extent buffer accessors Qu Wenruo
2020-09-15  5:35 ` [PATCH v2 09/19] btrfs: make csum_tree_block() handle sectorsize smaller than page size Qu Wenruo
2020-09-15  8:47   ` Johannes Thumshirn
2020-09-15  5:35 ` [PATCH v2 10/19] btrfs: add assert_spin_locked() for attach_extent_buffer_page() Qu Wenruo
2020-09-15  8:52   ` Johannes Thumshirn
2020-09-15  5:35 ` [PATCH v2 11/19] btrfs: extract the extent buffer verification from btree_readpage_end_io_hook() Qu Wenruo
2020-09-15  5:35 ` [PATCH v2 12/19] btrfs: extent_io: only require sector size alignment for page read Qu Wenruo
2020-09-15  5:35 ` [PATCH v2 13/19] btrfs: make btrfs_readpage_end_io_hook() follow sector size Qu Wenruo
2020-09-15  5:35 ` [PATCH v2 14/19] btrfs: make btree inode io_tree has its special owner Qu Wenruo
2020-09-16  9:28   ` Johannes Thumshirn
2020-09-16 16:06   ` David Sterba
2020-09-17  0:02     ` Qu Wenruo
2020-09-17 12:50       ` David Sterba
2020-09-18  8:18         ` Qu Wenruo
2020-09-22 14:06           ` David Sterba
2020-09-22 14:14   ` David Sterba
2020-09-15  5:35 ` [PATCH v2 15/19] btrfs: don't set extent_io_tree bits for btree inode at endio time Qu Wenruo
2020-09-15  5:35 ` [PATCH v2 16/19] btrfs: use extent_io_tree to handle subpage extent buffer allocation Qu Wenruo
2020-09-15  5:35 ` [PATCH v2 17/19] btrfs: implement subpage metadata read and its endio function Qu Wenruo
2020-09-16  8:47   ` kernel test robot
2020-09-15  5:35 ` [PATCH v2 18/19] btrfs: implement btree_readpage() and try_release_extent_buffer() for subpage Qu Wenruo
2020-09-15  5:35 ` [PATCH v2 19/19] btrfs: allow RO mount of 4K sector size fs on 64K page system Qu Wenruo
2020-09-16  1:35 ` [PATCH v2 00/19] btrfs: add read-only support for subpage sector size Qu Wenruo
2020-09-16 16:18 ` Neal Gompa
2020-09-17  0:03   ` Qu Wenruo
2020-09-17  0:13     ` Neal Gompa
2020-09-17  0:24       ` Qu Wenruo

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