From: "heming.zhao@suse.com" <heming.zhao@suse.com>
To: David Teigland <teigland@redhat.com>,
Martin Wilck <martin.wilck@suse.com>
Cc: "bmarzins@redhat.com" <bmarzins@redhat.com>,
"prajnoha@redhat.com" <prajnoha@redhat.com>,
"linux-lvm@redhat.com" <linux-lvm@redhat.com>,
"zkabelac@redhat.com" <zkabelac@redhat.com>
Subject: Re: [linux-lvm] Discussion: performance issue on event activation mode
Date: Tue, 19 Oct 2021 00:56:37 +0800 [thread overview]
Message-ID: <d0262d2d-1dbe-954c-80cf-10ed56fb58b6@suse.com> (raw)
In-Reply-To: <20211018150418.GA3917@redhat.com>
On 10/18/21 23:04, David Teigland wrote:
> On Mon, Oct 18, 2021 at 06:24:49AM +0000, Martin Wilck wrote:
>> I'd like to second Peter here, "RUN" is in general less fragile than
>> "IMPORT{PROGRAM}". You should use IMPORT{PROGRAM}" if and only if
>>
>> - the invoked program can work with incomplete udev state of a device
>> (the progrem should not try to access the device via
>> libudev, it should rather get properties either from sysfs or the
>> uevent's environment variables)
>> - you need the result or the output of the program in order to proceed
>> with rules processing.
>
> Those are both true in this case. I can't say I like it either, but udev
> rules force hacky solutions on us. I began trying to use RUN several
> months ago and I think I gave up trying to find a way to pass values from
> the RUN program back into the udev rule (possibly by writing values to a
> temp file and then doing IMPORT{file}). The udev rule needs the name of
> the VG to activate, and that name comes from the pvscan. For an even
> uglier form of this, see the equivalent I wrote for dracut:
> https://github.com/dracutdevs/dracut/pull/1567/files
>
> The latest version of the hybrid service+event activation is here
> https://sourceware.org/git/?p=lvm2.git;a=shortlog;h=refs/heads/dev-dct-activation-switch-7
>
> I've made it simple to edit lvm.conf to switch between:
> - activation from fixed services only
> - activation from events only
> - activation from fixes services first, then from events
For the branch code of dev-dct-activation-switch-7, If the comment before
event_activation_enable() is correct. option "event_activation" becomes useless.
I still prefer to use one switcher to control all behaviors.
>
> There are sure to be tradeoffs, we know that many concurrent activations
> from events are slow, and fixed services which are more serialized could
> be delayed from slow devices. I'm still undecided on the best default
> setting, i.e. which will work best for most people, and would welcome any
> thoughts or relevant experience.
>
from my test results, I never meet delay issue under serialized mode (except udev.children_max=1).
I prefer to set services first, then events. This style will triggers performance issue after
entering events mode, but this is under expectation.
Thanks,
Heming
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next prev parent reply other threads:[~2021-10-18 19:10 UTC|newest]
Thread overview: 86+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-06 6:15 [linux-lvm] Discussion: performance issue on event activation mode heming.zhao
2021-06-06 16:35 ` Roger Heflin
2021-06-07 10:27 ` Martin Wilck
2021-06-07 15:30 ` heming.zhao
2021-06-07 15:45 ` Martin Wilck
2021-06-07 20:52 ` Roger Heflin
2021-06-07 21:30 ` David Teigland
2021-06-08 8:26 ` Martin Wilck
2021-06-08 15:39 ` David Teigland
2021-06-08 15:47 ` Martin Wilck
2021-06-08 16:02 ` Zdenek Kabelac
2021-06-08 16:05 ` Martin Wilck
2021-06-08 16:03 ` David Teigland
2021-06-08 16:07 ` Martin Wilck
2021-06-15 17:03 ` David Teigland
2021-06-15 18:21 ` Zdenek Kabelac
2021-06-16 16:18 ` heming.zhao
2021-06-16 16:38 ` David Teigland
2021-06-17 3:46 ` heming.zhao
2021-06-17 15:27 ` David Teigland
2021-06-08 16:49 ` heming.zhao
2021-06-08 16:18 ` heming.zhao
2021-06-09 4:01 ` heming.zhao
2021-06-09 5:37 ` Heming Zhao
2021-06-09 18:59 ` David Teigland
2021-06-10 17:23 ` heming.zhao
2021-06-07 15:48 ` Martin Wilck
2021-06-07 16:31 ` Zdenek Kabelac
2021-06-07 21:48 ` David Teigland
2021-06-08 12:29 ` Peter Rajnoha
2021-06-08 13:23 ` Martin Wilck
2021-06-08 13:41 ` Peter Rajnoha
2021-06-08 13:46 ` Zdenek Kabelac
2021-06-08 13:56 ` Peter Rajnoha
2021-06-08 14:23 ` Zdenek Kabelac
2021-06-08 14:48 ` Martin Wilck
2021-06-08 15:19 ` Peter Rajnoha
2021-06-08 15:39 ` Martin Wilck
2021-09-09 19:44 ` David Teigland
2021-09-10 17:38 ` Martin Wilck
2021-09-12 16:51 ` heming.zhao
2021-09-27 10:00 ` Peter Rajnoha
2021-09-27 15:38 ` David Teigland
2021-09-28 6:34 ` Martin Wilck
2021-09-28 14:42 ` David Teigland
2021-09-28 15:16 ` Martin Wilck
2021-09-28 15:31 ` Martin Wilck
2021-09-28 15:56 ` David Teigland
2021-09-28 18:03 ` Benjamin Marzinski
2021-09-28 17:42 ` Benjamin Marzinski
2021-09-28 19:15 ` Martin Wilck
2021-09-29 22:06 ` Peter Rajnoha
2021-09-30 7:51 ` Martin Wilck
2021-09-30 8:07 ` heming.zhao
2021-09-30 9:31 ` Martin Wilck
2021-09-30 11:41 ` Peter Rajnoha
2021-09-30 15:32 ` heming.zhao
2021-10-01 7:41 ` Martin Wilck
2021-10-01 8:08 ` Peter Rajnoha
2021-09-30 11:29 ` Peter Rajnoha
2021-09-30 16:04 ` David Teigland
2021-09-30 14:41 ` Benjamin Marzinski
2021-10-01 7:42 ` Martin Wilck
2021-09-29 21:53 ` Peter Rajnoha
2021-09-30 7:45 ` Martin Wilck
2021-09-29 21:39 ` Peter Rajnoha
2021-09-30 7:22 ` Martin Wilck
2021-09-30 14:26 ` David Teigland
2021-09-30 15:55 ` David Teigland
2021-10-01 8:00 ` Peter Rajnoha
2021-10-18 6:24 ` Martin Wilck
2021-10-18 15:04 ` David Teigland
2021-10-18 16:56 ` heming.zhao [this message]
2021-10-18 21:51 ` Zdenek Kabelac
2021-10-19 17:18 ` David Teigland
2021-10-20 14:40 ` Martin Wilck
2021-10-20 14:50 ` David Teigland
2021-10-20 14:54 ` Martin Wilck
2021-10-20 15:12 ` David Teigland
2021-06-07 16:40 ` David Teigland
2021-07-02 21:09 ` David Teigland
2021-07-02 21:22 ` Martin Wilck
2021-07-02 22:02 ` David Teigland
2021-07-03 11:49 ` heming.zhao
2021-07-08 10:10 ` Tom Yan
2021-07-02 21:31 ` Tom Yan
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