From: NeilBrown <neilb@suse.com>
To: Artur Paszkiewicz <artur.paszkiewicz@intel.com>, shli@kernel.org
Cc: linux-raid@vger.kernel.org
Subject: Re: [PATCH v2 03/12] raid5-cache: add a new policy
Date: Wed, 07 Dec 2016 11:46:36 +1100 [thread overview]
Message-ID: <87d1h44lcj.fsf@notabene.neil.brown.name> (raw)
In-Reply-To: <20161205153113.7268-4-artur.paszkiewicz@intel.com>
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On Tue, Dec 06 2016, Artur Paszkiewicz wrote:
> Add a source file for the new policy implementation and allow selecting
> the policy based on the policy_type parameter in r5l_init_log().
>
> Introduce a new flag for rdev state flags to allow enabling the new
> policy from userspace.
This seems odd. Why is this a per-device flag?
It makes sense for "journal" to be a per-device flag, because only one
device is the journal device and it is obviously different from the
others.
But with the ppl, all devices serve as journal devices. So we would
need to set journal_ppl on all devices? What happens if you set it on
some, but not others? I see you get an error.
I think some sort of array-wide setting would make more sense, would it
not?
And what is an RWH??? A Really Weird Handle ??
I guess it is probably a Raid5 Write Hole ? At the very least there
should be a comment explaining this when you define the enum. (remember,
you are trying to make it easier for reviewers).
It might almost make sense for bitmap/metadata to be used here.
It can currently be "external" "internal" "clustered".
Allow also "journalled" or "partial-partiy-log" ???
Maybe not ... but I'd definitely prefer a global setting, and one that
didn't use an obscure abbreviation.
NeilBrown
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next prev parent reply other threads:[~2016-12-07 0:46 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-12-05 15:31 [PATCH v2 00/12] Partial Parity Log for MD RAID 5 Artur Paszkiewicz
2016-12-05 15:31 ` [PATCH v2 01/12] raid5-cache: move declarations to separate header Artur Paszkiewicz
2016-12-05 15:31 ` [PATCH v2 02/12] raid5-cache: add policy logic Artur Paszkiewicz
2016-12-05 15:31 ` [PATCH v2 03/12] raid5-cache: add a new policy Artur Paszkiewicz
2016-12-07 0:46 ` NeilBrown [this message]
2016-12-07 14:36 ` Artur Paszkiewicz
2016-12-07 23:24 ` NeilBrown
2016-12-08 10:28 ` Artur Paszkiewicz
2016-12-08 21:22 ` NeilBrown
2016-12-05 15:31 ` [PATCH v2 04/12] md: superblock changes for PPL Artur Paszkiewicz
2016-12-05 15:31 ` [PATCH v2 05/12] raid5-ppl: Partial Parity Log implementation Artur Paszkiewicz
2016-12-06 1:06 ` kbuild test robot
2016-12-07 1:17 ` NeilBrown
2016-12-07 14:37 ` Artur Paszkiewicz
2016-12-05 15:31 ` [PATCH v2 06/12] raid5-ppl: calculate partial parity Artur Paszkiewicz
2016-12-05 15:31 ` [PATCH v2 07/12] md: mddev_find_container helper function Artur Paszkiewicz
2016-12-07 1:23 ` NeilBrown
2016-12-05 15:31 ` [PATCH v2 08/12] md: expose rdev->sb_start as sysfs attribute Artur Paszkiewicz
2016-12-07 1:25 ` NeilBrown
2016-12-05 15:31 ` [PATCH v2 09/12] raid5-ppl: read PPL signature from IMSM metadata Artur Paszkiewicz
2016-12-07 1:25 ` NeilBrown
2016-12-07 14:38 ` Artur Paszkiewicz
2016-12-07 23:27 ` NeilBrown
2016-12-08 10:36 ` Artur Paszkiewicz
2016-12-05 15:31 ` [PATCH v2 10/12] raid5-ppl: recovery from dirty shutdown using PPL Artur Paszkiewicz
2016-12-05 15:31 ` [PATCH v2 11/12] raid5-ppl: support disk add/remove with distributed PPL Artur Paszkiewicz
2016-12-07 1:29 ` NeilBrown
2016-12-05 15:31 ` [PATCH v2 12/12] raid5-ppl: runtime PPL enabling or disabling Artur Paszkiewicz
2016-12-07 0:32 ` [PATCH v2 00/12] Partial Parity Log for MD RAID 5 NeilBrown
2016-12-07 14:36 ` Artur Paszkiewicz
2016-12-07 17:09 ` Shaohua Li
2016-12-13 15:25 ` Jes Sorensen
2016-12-14 19:47 ` Shaohua Li
2016-12-15 11:44 ` Artur Paszkiewicz
2016-12-16 23:24 ` Shaohua Li
2017-01-03 15:42 ` Jes Sorensen
2017-01-04 8:01 ` Artur Paszkiewicz
2017-01-04 13:29 ` Jes Sorensen
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