From: tada keisuke <keisuke1.tada@kioxia.com>
To: "song@kernel.org" <song@kernel.org>,
"yukuai3@huawei.com" <yukuai3@huawei.com>
Cc: "linux-raid@vger.kernel.org" <linux-raid@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: [PATCH 00/11] md: avoid counter operation conflicts
Date: Tue, 26 Mar 2024 10:29:16 +0000 [thread overview]
Message-ID: <a022f547c43e40e2b9f0aebb2bd0bfa8@kioxia.com> (raw)
Currently, active_aligned_reads and nr_pending used as counters are atomic types.
Therefore, when inc/dec in a multi-core results in conflicts.
To solve this problem, use "percpu_ref" counters that can avoid conflicts and maintain consistency.
Switch modes of percpu_ref to achieve both consistency and conflict avoidance.
During normal operations such as inc/dec, it operates as percpu mode.
When consistency is required, it operates as atomic mode.
The operations that require consistency are as follows:
・Zero check for the counter
・All operations in RAID 1/10
Patches 1, 3, 6 change active_aligned_reads, and patches 2, 4, 5, 7 to 11 change nr_pending.
nr_pending temporarily switch from percpu mode to atomic mode in patch 7.
This is to reduce the amount of changes from patches 8 to 10.
Finally, nr_pending switch from atomic mode to percpu mode in patch 11.
Keisuke TADA (11):
add infra for active_aligned_reads changes
add infra for nr_pending changes
workaround for inconsistency of config state in takeover
minimize execution of zero check for nr_pending
match the type of variables to percpu_ref
avoid conflicts in active_aligned_reads operations
change the type of nr_pending from atomic_t to percpu_ref
add atomic mode switching in RAID 1/10
add atomic mode switching when removing disk
add atomic mode switching when I/O completion
avoid conflicts in nr_pending operations
drivers/md/md-bitmap.c | 2 +-
drivers/md/md.c | 40 +++++++++++++++---
drivers/md/md.h | 62 ++++++++++++++++++++++++----
drivers/md/raid1.c | 37 +++++++++++------
drivers/md/raid10.c | 60 ++++++++++++++++-----------
drivers/md/raid5-cache.c | 4 +-
drivers/md/raid5.c | 89 +++++++++++++++++++++++++++-------------
drivers/md/raid5.h | 17 +++++++-
8 files changed, 230 insertions(+), 81 deletions(-)
base-commit: fcf3f7e2fc8a53a6140beee46ec782a4c88e4744
--
2.34.1
next reply other threads:[~2024-03-26 11:18 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-26 10:29 tada keisuke [this message]
2024-03-26 14:01 ` [PATCH 00/11] md: avoid counter operation conflicts Yu Kuai
2024-03-27 1:27 ` tada keisuke
2024-04-10 21:13 ` Song Liu
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