[linux-lvm] system boot time regression when using lvm2-2.03.05

[Heming Zhao]

Thanks for you reply.

I found the latest lvm2 git source code contains your 3 commits. So I 
built lvm2 with today's git code. But there is no big change as before.

ENV: fedora30 server edition, 896 PVs.

All below results from today's work.

[with patch]
event_activation = 1 && obtain_device_list_from_udev = 1
boot time: 1min 44.295s

event_activation = 0 && obtain_device_list_from_udev = 0
boot time: 59.759s

[without patch]
event_activation = 1 && obtain_device_list_from_udev = 1
boot time: 1min 56.040s

event_activation = 0 && obtain_device_list_from_udev = 0
boot time: 1min 6.715s

Thanks.

On 9/3/19 11:17 PM, David Teigland wrote:
> On Tue, Sep 03, 2019 at 05:02:25AM +0000, Heming Zhao wrote:
>> Test result URL:
>> https://gist.github.com/zhaohem/f9951bb016962cdd07bf7c9d3d7fd525
> 
> At least part of the problem is caused by lvm waiting on udev, e.g.
> WARNING: Device /dev/vdf76 not initialized in udev database even after waiting 10000000 microseconds.
> 
> I recently wrote this patch to stop that:
> https://sourceware.org/git/?p=lvm2.git;a=commitdiff;h=0534cd9cd4066c88a7dd815f2f3206a177169334
> 
> With this older patch, obtain_device_list_from_udev=0 can also help avoid it:
> https://sourceware.org/git/?p=lvm2.git;a=commitdiff;h=3ebce8dbd2d9afc031e0737f8feed796ec7a8df9
> 
> Also, I just pushed out this commit that makes the pvscan activations
> faster when there are many PVs:
> https://sourceware.org/git/?p=lvm2.git;a=commit;h=25b58310e3d606a85abc9bd50991ccb7ddcbfe25
> 
> Dave
>