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From: Nikolay Borisov <nborisov@suse.com>
To: Dennis Zhou <dennis@kernel.org>, David Sterba <dsterba@suse.com>,
	Josef Bacik <josef@toxicpanda.com>, Chris Mason <clm@fb.com>,
	Omar Sandoval <osandov@osandov.com>,
	Nick Terrell <terrelln@fb.com>
Cc: kernel-team@fb.com, linux-btrfs@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 07/11] btrfs: move to fn pointers for get/put workspaces
Date: Tue, 29 Jan 2019 10:22:34 +0200
Message-ID: <6f9b4be7-0ce8-bd62-c90d-f3f537528b7a@suse.com> (raw)
In-Reply-To: <20190128212437.11597-8-dennis@kernel.org>



On 28.01.19 г. 23:24 ч., Dennis Zhou wrote:
> The previous patch added generic helpers for get_workspace() and
> put_workspace(). Now, we can migrate ownership of the workspace_manager
> to be in the compression type code as the compression code itself
> doesn't care beyond being able to get a workspace. The init/cleanup
> and get/put methods are abstracted so each compression algorithm can
> decide how they want to manage their workspaces.
> 
> Signed-off-by: Dennis Zhou <dennis@kernel.org>

TBH I can't really see the value in this patch. IMO it doesn't make the
code more readable, on the contrary, you create algorithm-specific
wrappers over the generic function, where the sole specialization is in
the arguments passed to the generic functions. You introduce 4 more
function pointers and this affects performance negatively (albeit can't
say to what extent) due to spectre mitigations (retpolines).

I also read the follow up patches with the hopes of seeing how the code
becomes cleaner to no avail. At this point I'm really not in favor of
this particular patch.

  reply index

Thread overview: 46+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-01-28 21:24 [PATCH 00/11] btrfs: add zstd compression level support Dennis Zhou
2019-01-28 21:24 ` [PATCH 01/11] btrfs: add macros for compression type and level Dennis Zhou
2019-01-29  7:26   ` Nikolay Borisov
2019-01-29 17:57   ` Josef Bacik
2019-01-29 22:30   ` Omar Sandoval
2019-01-31 16:00   ` David Sterba
2019-01-31 16:17     ` Dennis Zhou
2019-01-28 21:24 ` [PATCH 02/11] btrfs: rename workspaces_list to workspace_manager Dennis Zhou
2019-01-29  7:27   ` Nikolay Borisov
2019-01-29 17:58   ` Josef Bacik
2019-01-28 21:24 ` [PATCH 03/11] btrfs: manage heuristic workspace as index 0 Dennis Zhou
2019-01-29  7:53   ` Nikolay Borisov
2019-01-29 22:43     ` Dennis Zhou
2019-01-29 18:02   ` Josef Bacik
2019-01-31 16:10   ` David Sterba
2019-01-28 21:24 ` [PATCH 04/11] btrfs: unify compression ops with workspace_manager Dennis Zhou
2019-01-29  7:54   ` Nikolay Borisov
2019-01-29 18:03   ` Josef Bacik
2019-01-28 21:24 ` [PATCH 05/11] btrfs: add helper methods for workspace manager init and cleanup Dennis Zhou
2019-01-29  7:58   ` Nikolay Borisov
2019-01-29 18:04   ` Josef Bacik
2019-01-28 21:24 ` [PATCH 06/11] btrfs: add compression interface in (get/put)_workspace() Dennis Zhou
2019-01-29 18:06   ` Josef Bacik
2019-01-28 21:24 ` [PATCH 07/11] btrfs: move to fn pointers for get/put workspaces Dennis Zhou
2019-01-29  8:22   ` Nikolay Borisov [this message]
2019-01-29 23:35     ` Dennis Zhou
2019-01-29 18:17   ` Josef Bacik
2019-01-29 18:44     ` Josef Bacik
2019-01-28 21:24 ` [PATCH 08/11] btrfs: plumb level through the compression interface Dennis Zhou
2019-01-29  8:08   ` Nikolay Borisov
2019-01-29 18:17   ` Josef Bacik
2019-01-28 21:24 ` [PATCH 09/11] btrfs: change set_level() to bound the level passed in Dennis Zhou
2019-01-29  8:14   ` Nikolay Borisov
2019-01-30 22:06     ` Dennis Zhou
2019-01-28 21:24 ` [PATCH 10/11] btrfs: zstd use the passed through level instead of default Dennis Zhou
2019-01-29  8:15   ` Nikolay Borisov
2019-01-28 21:24 ` [PATCH 11/11] btrfs: add zstd compression level support Dennis Zhou
2019-01-29  7:25   ` Nikolay Borisov
2019-01-29 22:50     ` Dennis Zhou
2019-01-31 18:10   ` David Sterba
2019-01-31 18:13   ` David Sterba
2019-01-29 17:18 ` [PATCH 00/11] " David Sterba
2019-01-29 21:12   ` Nick Terrell
2019-01-30 17:40   ` Dennis Zhou
2019-01-31 14:04     ` David Sterba
2019-01-31 15:56       ` Dennis Zhou

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