From: Benjamin Marzinski <bmarzins@redhat.com>
To: John Stoffel <john@stoffel.org>
Cc: device-mapper development <dm-devel@redhat.com>,
Martin Wilck <Martin.Wilck@suse.com>
Subject: Re: [PATCH 10/15] libmultipath: change how the checker async is set
Date: Tue, 21 Jan 2020 06:49:49 -0600 [thread overview]
Message-ID: <20200121124949.GU30153@octiron.msp.redhat.com> (raw)
In-Reply-To: <24102.2942.443422.59933@quad.stoffel.home>
On Mon, Jan 20, 2020 at 03:20:14PM -0500, John Stoffel wrote:
> >>>>> "Benjamin" == Benjamin Marzinski <bmarzins@redhat.com> writes:
>
> Benjamin> On Sat, Jan 18, 2020 at 12:43:49PM -0500, John Stoffel wrote:
> >> >>>>> "Benjamin" == Benjamin Marzinski <bmarzins@redhat.com> writes:
> >>
> Benjamin> The way that the checkers async mode worked in multipathd didn't make
> Benjamin> much sense. When multipathd starts up, all checker classes are in the
> Benjamin> sync mode, and any pathinfo() calls on devices would run the checker in
> Benjamin> sync mode. However, the First time a checker class was used in
> Benjamin> checkerloop, it would set that checker class to async (assuming
> Benjamin> force_sync wasn't set). After that, no matter when a checker from that
> Benjamin> class was called, it would always run in async mode. Multipathd doesn't
> Benjamin> need to run checkers in sync mode at all, so don't.
> >>
> >> Sorry, I had a hard time parsing this description, especially the last
> >> sentence. Do you mean that checkers should default to async then,
> >> instead of sync mode? And from looking at the code, don't you mean
> >> that you force sync mode? I guess the question is whether checker
> >> classes should default sync, or async. And if they move to async,
> >> should they stay there?
> >>
>
> Benjamin> Sorry. I mean that right now multipathd runs the checkers from pathinfo(),
> Benjamin> wait_for_pending_paths() and check_path(). When multipathd starts, all
> Benjamin> checkers are in sync mode. The first time a checker is run from
> Benjamin> check_path(), it is switched to async mode, and stays there for the rest
> Benjamin> of the time multipathd is runing.
>
> Benjamin> There is no need for multipathd to run checkers in sync mode at all, so
> Benjamin> we shouldn't be doing so for these first checks.
>
> Thanks, that makes the entire issue much more clear. This raises the
> question of why there is a sync mode at all then? In any case, the
> above makes the issue more understandable.
The multipath command, which uses the same checkers, runs in sync mode.
-Ben
>
> John
next prev parent reply other threads:[~2020-01-21 12:49 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-17 2:18 [PATCH 00/15] Multipath patch dump Benjamin Marzinski
2020-01-17 2:18 ` [PATCH 01/15] multipathd: warn when configuration has been changed Benjamin Marzinski
2020-01-17 15:45 ` Martin Wilck
2020-01-22 11:59 ` Benjamin Marzinski
2020-01-17 15:51 ` Martin Wilck
2020-01-17 2:18 ` [PATCH 02/15] libmultipath: fix leak in foreign code Benjamin Marzinski
2020-01-17 15:50 ` Martin Wilck
2020-01-17 2:18 ` [PATCH 03/15] Fix leak in mpathpersist Benjamin Marzinski
2020-01-17 15:53 ` Martin Wilck
2020-01-17 2:18 ` [PATCH 04/15] libmultipath: remove unused path->prio_args Benjamin Marzinski
2020-01-17 15:55 ` Martin Wilck
2020-01-17 2:18 ` [PATCH 05/15] libmultipath: constify get_unaligned_be* Benjamin Marzinski
2020-01-17 15:57 ` Martin Wilck
2020-01-17 2:18 ` [PATCH 06/15] libmultipath: add missing hwe mpe variable merges Benjamin Marzinski
2020-01-17 16:04 ` Martin Wilck
2020-01-17 2:18 ` [PATCH 07/15] libmultipath: fix sgio_get_vpd looping Benjamin Marzinski
2020-01-17 16:27 ` Martin Wilck
2020-01-20 16:59 ` Benjamin Marzinski
2020-01-17 2:18 ` [PATCH 08/15] libmultipath: add vend_id to get_vpd_sgio Benjamin Marzinski
2020-01-17 16:58 ` Martin Wilck
2020-01-17 2:18 ` [PATCH 09/15] libmultipath: add code to get vendor specific vpd data Benjamin Marzinski
2020-01-17 16:56 ` Martin Wilck
2020-01-22 8:51 ` Benjamin Marzinski
2020-01-22 11:52 ` Martin Wilck
2020-01-22 12:20 ` Benjamin Marzinski
2020-01-18 17:34 ` John Stoffel
2020-01-22 9:46 ` Benjamin Marzinski
2020-01-17 2:18 ` [PATCH 10/15] libmultipath: change how the checker async is set Benjamin Marzinski
2020-01-17 17:02 ` Martin Wilck
2020-01-17 17:04 ` Martin Wilck
2020-01-18 17:43 ` John Stoffel
2020-01-20 15:07 ` Benjamin Marzinski
2020-01-20 20:20 ` John Stoffel
2020-01-21 12:49 ` Benjamin Marzinski [this message]
2020-01-21 20:13 ` John Stoffel
2020-01-17 2:18 ` [PATCH 11/15] libmultipath: change failed path prio timeout Benjamin Marzinski
2020-01-17 17:18 ` Martin Wilck
2020-01-20 16:22 ` Benjamin Marzinski
2020-01-17 2:18 ` [PATCH 12/15] multipathd: add new paths under vecs lock Benjamin Marzinski
2020-01-17 17:39 ` Martin Wilck
2020-01-17 2:18 ` [PATCH 13/15] libmultipath: add new checker class functions Benjamin Marzinski
2020-01-17 17:41 ` Martin Wilck
2020-01-17 2:18 ` [PATCH 14/15] libmultipath: make directio checker share io contexts Benjamin Marzinski
2020-01-20 8:09 ` Martin Wilck
2020-01-20 16:08 ` Benjamin Marzinski
2020-01-21 8:55 ` Martin Wilck
2020-01-17 2:18 ` [PATCH 15/15] tests: add directio unit tests Benjamin Marzinski
2020-01-20 8:27 ` Martin Wilck
2020-01-20 15:25 ` Benjamin Marzinski
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