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#1 2021-02-20 16:54:04

zerophase
Member
Registered: 2015-09-03
Posts: 200

Is there any means of only partially initializing ram at boot up?

I have 128 gigs of ram, and I'm pretty sure that's the major bottleneck in my boot times. Is there a means of configuring the kernel to only initialize so much ram during boot, and bring the rest online after booting has finished?

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#2 2021-02-20 17:05:45

V1del
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Registered: 2012-10-16
Posts: 13,024

Re: Is there any means of only partially initializing ram at boot up?

I highly doubt that to be an issue. Check with

systemd analyze critical-chain
sudo journalctl -b

on whether you find something to be more likely, like a visible time gab in relevant journal entries or services that actually delay you.

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#3 2021-02-20 17:36:11

zerophase
Member
Registered: 2015-09-03
Posts: 200

Re: Is there any means of only partially initializing ram at boot up?

V1del wrote:

I highly doubt that to be an issue. Check with

systemd analyze critical-chain
sudo journalctl -b

on whether you find something to be more likely, like a visible time gab in relevant journal entries or services that actually delay you.

My understanding is addressing all of that ram takes significant time. I don't know how much can be done with the kernel considering stabilizing that ram is done by the bios first.

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#4 2021-02-20 17:57:36

V1del
Forum Moderator
Registered: 2012-10-16
Posts: 13,024

Re: Is there any means of only partially initializing ram at boot up?

You can use mem=nnKMG /memmap parameters to define what the kernel sees where, and if it's just about a test to check whether this is an issue you could probably just opt for a smaller mem= value.

I do doubt whether that will actually be notable towards system boot time.

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#5 2021-02-20 18:01:01

zerophase
Member
Registered: 2015-09-03
Posts: 200

Re: Is there any means of only partially initializing ram at boot up?

V1del wrote:

You can use mem=nnKMG /memmap parameters to define what the kernel sees where, and if it's just about a test to check whether this is an issue you could probably just opt for a smaller mem= value.

I do doubt whether that will actually be notable towards system boot time.

Probably only matters for the bios. I added a good 15 seconds going from 64GB 3200 ram to 128GB 2400 ram. (can't run it at max speed, which is equivalent)

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#6 2021-02-20 21:21:03

seth
Member
Registered: 2012-09-03
Posts: 21,198

Re: Is there any means of only partially initializing ram at boot up?

The BIOS typically provides a fast boot option (that's not windows fast boot!) which will skip an initial memory test (by the BIOS)
It's unlikely that more RAM makes the kernel itself boot slower.

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#7 2021-02-20 21:38:16

zerophase
Member
Registered: 2015-09-03
Posts: 200

Re: Is there any means of only partially initializing ram at boot up?

seth wrote:

The BIOS typically provides a fast boot option ... which will skip an initial memory test (by the BIOS).

I have a feature turned on to get my ram stable. I think it's Asus's performance tuning mode 4 or something. Wish I knew what it did. My current memory controller is too weak to support 128 gigs at 3200 speeds, even with severely loosened timings.  Dropped bandwidth a lot and tightened timings as much as I could.

In general I'm always looking for little tweaks to boot a bit faster, though.

Last edited by zerophase (2021-02-20 21:39:23)

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#8 2021-02-20 21:45:32

seth
Member
Registered: 2012-09-03
Posts: 21,198

Re: Is there any means of only partially initializing ram at boot up?

What board in particular?
Check "sudo dmidecode"

However, time that is spent before the kernel starts cannot be cut by anything you do to the kernel.
=> When do you lose the  time?
https://bbs.archlinux.org/viewtopic.php … 0#p1957460

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#9 2021-02-21 00:28:20

Maniaxx
Member
From: .de
Registered: 2014-05-14
Posts: 426

Re: Is there any means of only partially initializing ram at boot up?

And forget about the 3200 vs 2400 speed difference. You won't notice that on boot times let alone 15 seconds difference.
Are you sure we are talking about 128GB and not 128MB?

Last edited by Maniaxx (2021-02-21 00:29:08)


sys2064

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#10 2021-05-03 12:12:06

zerophase
Member
Registered: 2015-09-03
Posts: 200

Re: Is there any means of only partially initializing ram at boot up?

seth wrote:

What board in particular?
Check "sudo dmidecode"

However, time that is spent before the kernel starts cannot be cut by anything you do to the kernel.
=> When do you lose the  time?
https://bbs.archlinux.org/viewtopic.php … 0#p1957460

Rampage V Extreme

Maniaxx wrote:

And forget about the 3200 vs 2400 speed difference. You won't notice that on boot times let alone 15 seconds difference.
Are you sure we are talking about 128GB and not 128MB?

128 gb.

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#11 2021-05-03 13:42:23

seth
Member
Registered: 2012-09-03
Posts: 21,198

Re: Is there any means of only partially initializing ram at boot up?

seth wrote:

However, time that is spent before the kernel starts cannot be cut by anything you do to the kernel.
=> When do you lose the  time?
https://bbs.archlinux.org/viewtopic.php … 0#p1957460

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