[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <34b04a5f-7ef8-4e00-b1c6-c4e692281499@molgen.mpg.de>
Date: Thu, 22 Feb 2024 09:40:07 +0100
From: Paul Menzel <pmenzel@...gen.mpg.de>
To: Kuai Yu <yukuai1@...weicloud.com>,
Paul E Luse <paul.e.luse@...ux.intel.com>
Cc: song@...nel.org, neilb@...e.com, shli@...com, linux-raid@...r.kernel.org,
linux-kernel@...r.kernel.org, yukuai3@...wei.com, yi.zhang@...wei.com,
yangerkun@...wei.com
Subject: Re: [PATCH md-6.9 00/10] md/raid1: refactor read_balance() and some
minor fix
Dear Kuai, dear Paul,
Thank you for your work. Some nits and request for benchmarks below.
Am 22.02.24 um 08:57 schrieb Yu Kuai:
> From: Yu Kuai <yukuai3@...wei.com>
>
> The orignial idea is that Paul want to optimize raid1 read
original
> performance([1]), however, we think that the orignial code for
original
> read_balance() is quite complex, and we don't want to add more
> complexity. Hence we decide to refactor read_balance() first, to make
> code cleaner and easier for follow up.
>
> Before this patchset, read_balance() has many local variables and many
> braches, it want to consider all the scenarios in one iteration. The
branches
> idea of this patch is to devide them into 4 different steps:
divide
> 1) If resync is in progress, find the first usable disk, patch 5;
> Otherwise:
> 2) Loop through all disks and skipping slow disks and disks with bad
> blocks, choose the best disk, patch 10. If no disk is found:
> 3) Look for disks with bad blocks and choose the one with most number of
> sectors, patch 8. If no disk is found:
> 4) Choose first found slow disk with no bad blocks, or slow disk with
> most number of sectors, patch 7.
>
> Note that step 3) and step 4) are super code path, and performance
> should not be considered.
>
> And after this patchset, we'll continue to optimize read_balance for
> step 2), specifically how to choose the best rdev to read.
Is there a change in performance with the current patch set? Is radi1
well enough covered by the test suite?
Kind regards,
Paul
> [1] https://lore.kernel.org/all/20240102125115.129261-1-paul.e.luse@linux.intel.com/
>
> Yu Kuai (10):
> md: add a new helper rdev_has_badblock()
> md: record nonrot rdevs while adding/removing rdevs to conf
> md/raid1: fix choose next idle in read_balance()
> md/raid1-10: add a helper raid1_check_read_range()
> md/raid1-10: factor out a new helper raid1_should_read_first()
> md/raid1: factor out read_first_rdev() from read_balance()
> md/raid1: factor out choose_slow_rdev() from read_balance()
> md/raid1: factor out choose_bb_rdev() from read_balance()
> md/raid1: factor out the code to manage sequential IO
> md/raid1: factor out helpers to choose the best rdev from
> read_balance()
>
> drivers/md/md.c | 28 ++-
> drivers/md/md.h | 12 ++
> drivers/md/raid1-10.c | 69 +++++++
> drivers/md/raid1.c | 454 ++++++++++++++++++++++++------------------
> drivers/md/raid10.c | 66 ++----
> drivers/md/raid5.c | 35 ++--
> 6 files changed, 402 insertions(+), 262 deletions(-)
Powered by blists - more mailing lists