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From: Christoph Hellwig <hch@infradead.org>
To: Qu Wenruo <wqu@suse.com>
Cc: linux-btrfs@vger.kernel.org
Subject: Re: [PoC PATCH 00/11] btrfs: scrub: rework to get rid of the complex bio formshaping
Date: Tue, 6 Dec 2022 00:40:44 -0800	[thread overview]
Message-ID: <Y48ADI5Qa2Wt+/JR@infradead.org> (raw)
In-Reply-To: <cover.1670314744.git.wqu@suse.com>

On Tue, Dec 06, 2022 at 04:23:27PM +0800, Qu Wenruo wrote:
> TL;DR
> The current scrub code is way too complex for future expansion.
> 
> Current scrub code has a complex system to manage its in-flight bios.

From my own ventures into that code I have to agree.

> This behavior is designed to improve scrub performance, but has a lot of
> disadvantage too:

Just curious:  any idea how it was supposed to improve performance?
Because the code does not actually look particularly optimized in terms
of I/O patterns.

> Furthermore, all work will done in a submit-and-wait fashion, reducing
> the delayed calls/jumps to minimal.

I think even with this overall scheme we could do a bit of async
state machine if needed.  But then again scrube is not the main
I/O fast path, so in doubt we can just throw more threads at the
problem if that becomes too complicated.

  parent reply	other threads:[~2022-12-06  8:40 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-12-06  8:23 [PoC PATCH 00/11] btrfs: scrub: rework to get rid of the complex bio formshaping Qu Wenruo
2022-12-06  8:23 ` [PoC PATCH 01/11] btrfs: scrub: introduce the structure for new BTRFS_STRIPE_LEN based interface Qu Wenruo
2022-12-06  8:23 ` [PoC PATCH 02/11] btrfs: scrub: introduce a helper to find and fill the sector info for a scrub2_stripe Qu Wenruo
2022-12-06  8:23 ` [PoC PATCH 03/11] btrfs: scrub: introduce a helper to verify one scrub2_stripe Qu Wenruo
2022-12-06  8:23 ` [PoC PATCH 04/11] btrfs: scrub: add the repair function for scrub2_stripe Qu Wenruo
2022-12-06  8:23 ` [PoC PATCH 05/11] btrfs: scrub: add a writeback helper " Qu Wenruo
2022-12-06  8:45   ` Christoph Hellwig
2022-12-06  8:23 ` [PoC PATCH 06/11] btrfs: scrub: add the error reporting " Qu Wenruo
2022-12-06 18:48   ` kernel test robot
2022-12-06  8:23 ` [PoC PATCH 07/11] btrfs: scrub: add raid56 P/Q scrubbing support Qu Wenruo
2022-12-27 10:45   ` kernel test robot
2022-12-06  8:23 ` [PoC PATCH 08/11] btrfs: scrub: use dedicated super block verification function to scrub one super block Qu Wenruo
2022-12-06  8:23 ` [PoC PATCH 09/11] btrfs: scrub: switch to the new scrub2_stripe based infrastructure Qu Wenruo
2022-12-06  8:23 ` [PoC PATCH 10/11] btrfs: scrub: cleanup the old scrub_parity infrastructure Qu Wenruo
2022-12-06  8:23 ` [PoC PATCH 11/11] btrfs: scrub: cleanup scrub_extent() and its related functions Qu Wenruo
2022-12-06  8:40 ` Christoph Hellwig [this message]
2022-12-06  9:29   ` [PoC PATCH 00/11] btrfs: scrub: rework to get rid of the complex bio formshaping Qu Wenruo
2022-12-13 22:08 ` Josef Bacik

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