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From: Naohiro Aota <naohiro.aota@wdc.com>
To: Josef Bacik <josef@toxicpanda.com>
Cc: linux-btrfs@vger.kernel.org, dsterba@suse.com, hare@suse.com,
	linux-fsdevel@vger.kernel.org,
	Johannes Thumshirn <johannes.thumshirn@wdc.com>
Subject: Re: [PATCH v9 38/41] btrfs: extend zoned allocator to use dedicated tree-log block group
Date: Tue, 10 Nov 2020 15:37:41 +0900	[thread overview]
Message-ID: <20201110063741.reca4c72vglfylvw@naota.dhcp.fujisawa.hgst.com> (raw)
In-Reply-To: <eb8f83f2-fb59-2b65-66e2-18cd0ecd1e02@toxicpanda.com>

On Tue, Nov 03, 2020 at 03:47:33PM -0500, Josef Bacik wrote:
>On 10/30/20 9:51 AM, Naohiro Aota wrote:
>>This is the 1/3 patch to enable tree log on ZONED mode.
>>
>>The tree-log feature does not work on ZONED mode as is. Blocks for a
>>tree-log tree are allocated mixed with other metadata blocks, and btrfs
>>writes and syncs the tree-log blocks to devices at the time of fsync(),
>>which is different timing from a global transaction commit. As a result,
>>both writing tree-log blocks and writing other metadata blocks become
>>non-sequential writes that ZONED mode must avoid.
>>
>>We can introduce a dedicated block group for tree-log blocks so that
>>tree-log blocks and other metadata blocks can be separated write streams.
>>As a result, each write stream can now be written to devices separately.
>>"fs_info->treelog_bg" tracks the dedicated block group and btrfs assign
>>"treelog_bg" on-demand on tree-log block allocation time.
>>
>>This commit extends the zoned block allocator to use the block group.
>>
>>Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
>>Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
>
>If you're going to remove an entire block group from being allowed to 
>be used for metadata you are going to need to account for it in the 
>space_info, otherwise we're going to end up with nasty ENOSPC corners 
>here.

Indeed. I'll add a dedicated space_info for treelog or, at least, separate
the block group from other metadata space_info. But, I'll address this
later in v11.

>
>But this begs the question, do we want the tree log for zoned?  We 
>could just commit the transaction and call it good enough.  We lose 
>performance, but zoned isn't necessarily about performance.

We have a large performance drop without tree-log (-o notreelog). Here is a
dbench (32 clients) result on SMR HDD.

With treelog:    153.509  MB/s	
Without treelog:  21.9651 MB/s

So, there is 85% drop of the throughput. I think this degradation is too large.

>
>If we do then at a minimum we're going to need to remove this block 
>group from the space info counters for metadata.  Thanks,
>
>Josef

  reply	other threads:[~2020-11-10  6:37 UTC|newest]

Thread overview: 119+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-30 13:51 [PATCH v9 00/41] btrfs: zoned block device support Naohiro Aota
2020-10-30 13:51 ` [PATCH v9 01/41] block: add bio_add_zone_append_page Naohiro Aota
2020-10-30 13:51   ` [PATCH v9 02/41] iomap: support REQ_OP_ZONE_APPEND Naohiro Aota
2020-11-02  5:34     ` Naohiro Aota
2020-11-02 16:55     ` Darrick J. Wong
2020-11-02 17:39       ` Johannes Thumshirn
2020-10-30 13:51   ` [PATCH v9 03/41] btrfs: introduce ZONED feature flag Naohiro Aota
2020-10-30 13:51   ` [PATCH v9 04/41] btrfs: Get zone information of zoned block devices Naohiro Aota
2020-11-02 16:53     ` Josef Bacik
2020-11-02 16:58       ` Johannes Thumshirn
2020-11-02 21:07       ` Naohiro Aota
2020-11-03 12:02     ` David Sterba
2020-10-30 13:51   ` [PATCH v9 05/41] btrfs: Check and enable ZONED mode Naohiro Aota
2020-11-03 12:13     ` David Sterba
2020-11-06  9:36       ` Naohiro Aota
2020-10-30 13:51   ` [PATCH v9 06/41] btrfs: introduce max_zone_append_size Naohiro Aota
2020-11-02 16:57     ` Josef Bacik
2020-11-03 12:16     ` David Sterba
2020-10-30 13:51   ` [PATCH v9 07/41] btrfs: disallow space_cache in ZONED mode Naohiro Aota
2020-11-02 17:02     ` Josef Bacik
2020-11-02 17:37       ` Johannes Thumshirn
2020-11-03 12:48     ` David Sterba
2020-11-10 10:14       ` Naohiro Aota
2020-10-30 13:51   ` [PATCH v9 08/41] btrfs: disallow NODATACOW " Naohiro Aota
2020-11-02 17:05     ` Josef Bacik
2020-11-03 12:57     ` David Sterba
2020-10-30 13:51   ` [PATCH v9 09/41] btrfs: disable fallocate " Naohiro Aota
2020-11-03 13:00     ` David Sterba
2020-10-30 13:51   ` [PATCH v9 10/41] btrfs: disallow mixed-bg " Naohiro Aota
2020-11-03 13:01     ` David Sterba
2020-10-30 13:51   ` [PATCH v9 11/41] btrfs: implement log-structured superblock for " Naohiro Aota
2020-11-02 18:22     ` Josef Bacik
2020-11-02 18:53       ` Johannes Thumshirn
2020-11-02 19:01         ` Josef Bacik
2020-11-02 19:31           ` Johannes Thumshirn
2020-11-03  8:21       ` Naohiro Aota
2020-11-02 18:54     ` Josef Bacik
2020-11-03  3:31       ` Naohiro Aota
2020-11-03 13:15     ` David Sterba
2020-11-03 14:10     ` David Sterba
2020-11-06 10:37       ` Naohiro Aota
2020-10-30 13:51   ` [PATCH v9 12/41] btrfs: implement zoned chunk allocator Naohiro Aota
2020-11-02 20:09     ` Josef Bacik
2020-11-02 22:21       ` Naohiro Aota
2020-11-03 13:23     ` David Sterba
2020-10-30 13:51   ` [PATCH v9 13/41] btrfs: verify device extent is aligned to zone Naohiro Aota
2020-11-02 20:14     ` Josef Bacik
2020-10-30 13:51   ` [PATCH v9 14/41] btrfs: load zone's alloction offset Naohiro Aota
2020-11-02 20:25     ` Josef Bacik
2020-11-02 20:29       ` Josef Bacik
2020-11-02 22:43         ` Naohiro Aota
2020-11-02 22:40       ` Naohiro Aota
2020-11-03 13:28     ` David Sterba
2020-10-30 13:51   ` [PATCH v9 15/41] btrfs: emulate write pointer for conventional zones Naohiro Aota
2020-11-02 20:37     ` Josef Bacik
2020-11-03  1:25       ` Naohiro Aota
2020-11-03 13:32     ` David Sterba
2020-10-30 13:51   ` [PATCH v9 16/41] btrfs: track unusable bytes for zones Naohiro Aota
2020-11-03 14:25     ` Josef Bacik
2020-10-30 13:51   ` [PATCH v9 17/41] btrfs: do sequential extent allocation in ZONED mode Naohiro Aota
2020-11-03 14:28     ` Josef Bacik
2020-10-30 13:51   ` [PATCH v9 18/41] btrfs: reset zones of unused block groups Naohiro Aota
2020-11-03 14:34     ` Josef Bacik
2020-11-10 10:40       ` Naohiro Aota
2020-10-30 13:51   ` [PATCH v9 19/41] btrfs: redirty released extent buffers in ZONED mode Naohiro Aota
2020-11-03 14:41     ` Josef Bacik
2020-11-06  9:11       ` Johannes Thumshirn
2020-11-06 15:01         ` Josef Bacik
2020-10-30 13:51   ` [PATCH v9 20/41] btrfs: extract page adding function Naohiro Aota
2020-11-03 14:45     ` Josef Bacik
2020-10-30 13:51   ` [PATCH v9 21/41] btrfs: use bio_add_zone_append_page for zoned btrfs Naohiro Aota
2020-11-03 14:55     ` Josef Bacik
2020-11-10 10:42       ` Naohiro Aota
2020-10-30 13:51   ` [PATCH v9 22/41] btrfs: handle REQ_OP_ZONE_APPEND as writing Naohiro Aota
2020-11-03 14:57     ` Josef Bacik
2020-10-30 13:51   ` [PATCH v9 23/41] btrfs: split ordered extent when bio is sent Naohiro Aota
2020-11-03 15:29     ` Josef Bacik
2020-10-30 13:51   ` [PATCH v9 24/41] btrfs: extend btrfs_rmap_block for specifying a device Naohiro Aota
2020-11-03 15:32     ` Josef Bacik
2020-11-06 10:52       ` Johannes Thumshirn
2020-10-30 13:51   ` [PATCH v9 25/41] btrfs: use ZONE_APPEND write for ZONED btrfs Naohiro Aota
2020-11-03 15:55     ` Josef Bacik
2020-10-30 13:51   ` [PATCH v9 26/41] btrfs: enable zone append writing for direct IO Naohiro Aota
2020-11-03 15:56     ` Josef Bacik
2020-10-30 13:51   ` [PATCH v9 27/41] btrfs: introduce dedicated data write path for ZONED mode Naohiro Aota
2020-11-03 15:57     ` Josef Bacik
2020-10-30 13:51   ` [PATCH v9 28/41] btrfs: serialize meta IOs on " Naohiro Aota
2020-11-03 16:04     ` Josef Bacik
2020-10-30 13:51   ` [PATCH v9 29/41] btrfs: wait existing extents before truncating Naohiro Aota
2020-10-30 13:51   ` [PATCH v9 30/41] btrfs: avoid async metadata checksum on ZONED mode Naohiro Aota
2020-11-03 16:05     ` Josef Bacik
2020-10-30 13:51   ` [PATCH v9 31/41] btrfs: mark block groups to copy for device-replace Naohiro Aota
2020-11-03 17:09     ` Josef Bacik
2020-10-30 13:51   ` [PATCH v9 32/41] btrfs: implement cloning for ZONED device-replace Naohiro Aota
2020-11-03 17:15     ` Josef Bacik
2020-10-30 13:51   ` [PATCH v9 33/41] btrfs: implement copying " Naohiro Aota
2020-11-03 17:19     ` Josef Bacik
2020-11-10 11:09       ` Naohiro Aota
2020-10-30 13:51   ` [PATCH v9 34/41] btrfs: support dev-replace in ZONED mode Naohiro Aota
2020-11-03 20:34     ` Josef Bacik
2020-10-30 13:51   ` [PATCH v9 35/41] btrfs: enable relocation " Naohiro Aota
2020-11-03 20:39     ` Josef Bacik
2020-10-30 13:51   ` [PATCH v9 36/41] btrfs: relocate block group to repair IO failure in ZONED Naohiro Aota
2020-10-30 13:51   ` [PATCH v9 37/41] btrfs: split alloc_log_tree() Naohiro Aota
2020-11-03 20:42     ` Josef Bacik
2020-11-03 22:10       ` Amy Parker
2020-11-10 11:12         ` Naohiro Aota
2020-10-30 13:51   ` [PATCH v9 38/41] btrfs: extend zoned allocator to use dedicated tree-log block group Naohiro Aota
2020-11-03 20:47     ` Josef Bacik
2020-11-10  6:37       ` Naohiro Aota [this message]
2020-10-30 13:51   ` [PATCH v9 39/41] btrfs: serialize log transaction on ZONED mode Naohiro Aota
2020-11-03 20:49     ` Josef Bacik
2020-10-30 13:51   ` [PATCH v9 40/41] btrfs: reorder log node allocation Naohiro Aota
2020-11-03 20:49     ` Josef Bacik
2020-10-30 13:51   ` [PATCH v9 41/41] btrfs: enable to mount ZONED incompat flag Naohiro Aota
2020-10-31  3:40   ` [PATCH v9 01/41] block: add bio_add_zone_append_page Jens Axboe
2020-11-02  5:15     ` Naohiro Aota
2020-11-02  8:24     ` Johannes Thumshirn
2020-11-03 11:54 ` [PATCH v9 00/41] btrfs: zoned block device support David Sterba

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