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From: Tom Yan <tom.ty89@gmail.com>
To: LVM general discussion and development <linux-lvm@redhat.com>
Cc: Zdenek Kabelac <zkabelac@redhat.com>,
	Martin Wilck <martin.wilck@suse.com>,
	"heming.zhao@suse.com" <heming.zhao@suse.com>
Subject: Re: [linux-lvm] Discussion: performance issue on event activation mode
Date: Sat, 3 Jul 2021 05:31:09 +0800	[thread overview]
Message-ID: <CAGnHSE=GJ7UFMDPFqkrp4Y6604BccRQn-a_KA4iTeuOe0_hwUQ@mail.gmail.com> (raw)
In-Reply-To: <20210702210903.GA15057@redhat.com>

On Sat, 3 Jul 2021 at 05:17, David Teigland <teigland@redhat.com> wrote:
>
> On Sun, Jun 06, 2021 at 02:15:23PM +0800, heming.zhao@suse.com wrote:
> > dev_cache_scan //order: O(n^2)
> >  + _insert_dirs //O(n)
> >  | if obtain_device_list_from_udev() true
> >  |   _insert_udev_dir //O(n)
> >  |
> >  + dev_cache_index_devs //O(n)
>
> I've been running some experiments and trying some patches to improve
> this.  By setting obtain_device_list_from_udev=0, and using the attached
> patch to disable dev_cache_index_devs, the pvscan is much better.
>
> systemctl status lvm2-pvscan appears to show that the pvscan command
> itself runs for only 2-4 seconds, while the service as a whole takes
> around 15 seconds.  See the 16 sec gap below from the end of pvscan
> to the systemd Started message.  If that's accurate, the remaining delay
> would lie outside lvm.

Not necessarily. It could be pvscan stalling for 16s after printing
the "now active" message for some reason before exiting (with 0).

>
> Jul 02 15:27:57 localhost.localdomain systemd[1]: Starting LVM event activation on device 253:1710...
> Jul 02 15:28:00 localhost.localdomain lvm[65620]:   pvscan[65620] PV /dev/mapper/mpathalz online, VG 1ed02c7d-0019-43c4-91b5-f220f3521ba9 is complete.
> Jul 02 15:28:00 localhost.localdomain lvm[65620]:   pvscan[65620] VG 1ed02c7d-0019-43c4-91b5-f220f3521ba9 run autoactivation.
> Jul 02 15:28:00 localhost.localdomain lvm[65620]:   1 logical volume(s) in volume group "1ed02c7d-0019-43c4-91b5-f220f3521ba9" now active
> Jul 02 15:28:16 localhost.localdomain systemd[1]: Started LVM event activation on device 253:1710.
>
> _______________________________________________
> linux-lvm mailing list
> linux-lvm@redhat.com
> https://listman.redhat.com/mailman/listinfo/linux-lvm
> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/

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read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/


      parent reply	other threads:[~2021-07-02 21:31 UTC|newest]

Thread overview: 87+ 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                       ` [dm-devel] " Martin Wilck
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
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 [this message]

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