From: "heming.zhao@suse.com" <heming.zhao@suse.com>
To: Martin Wilck <martin.wilck@suse.com>,
"linux-lvm@redhat.com" <linux-lvm@redhat.com>,
"rogerheflin@gmail.com" <rogerheflin@gmail.com>
Cc: "teigland@redhat.com" <teigland@redhat.com>,
"zkabelac@redhat.com" <zkabelac@redhat.com>
Subject: Re: [linux-lvm] Discussion: performance issue on event activation mode
Date: Mon, 7 Jun 2021 23:30:25 +0800 [thread overview]
Message-ID: <7522886d-bfba-6dd6-882a-703d5776e71f@suse.com> (raw)
In-Reply-To: <dd395e820a4cf9b5e807e8de1e456786eebd2044.camel@suse.com>
On 6/7/21 6:27 PM, Martin Wilck wrote:
> On So, 2021-06-06 at 11:35 -0500, Roger Heflin wrote:
>> This might be a simpler way to control the number of threads at the
>> same time.
>>
>> On large machines (cpu wise, memory wise and disk wise). I have
>> only seen lvm timeout when udev_children is set to default. The
>> default seems to be set wrong, and the default seemed to be tuned for
>> a case where a large number of the disks on the machine were going to
>> be timing out (or otherwise really really slow), so to support this
>> case a huge number of threads was required.. I found that with it
>> set to default on a close to 100 core machine that udev got about 87
>> minutes of time during the boot up (about 2 minutes). Changing the
>> number of children to =4 resulted in udev getting around 2-3 minutes
>> in the same window, and actually resulted in a much faster boot up
>> and a much more reliable boot up (no timeouts).
>
> Wow, setting the number of children to 4 is pretty radical. We decrease
> this parameter often on large machines, but we never went all the way
> down to a single-digit number. If that's really necessary under
> whatever circumstances, it's clear evidence of udev's deficiencies.
>
> I am not sure if it's better than Heming's suggestion though. It would
> affect every device in the system. It wouldn't even be possible to
> process more than 4 totally different events at the same time.
>
hello
I tested udev.children_max with value 1, 2 & 4. The results showed it
didn't take effect, and the booting time even longer than before.
This solution may suite for some special cases.
(my env: kvm-qemu vm, 6vpu, 22G mem, 1015 disks)
Regards
heming
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next prev parent reply other threads:[~2021-06-07 15:31 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 [this message]
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
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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