Author Topic: Fedora 35 (was F-34): going to 4k page size? Help needed  (Read 1912 times)

pocock

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Fedora 35 (was F-34): going to 4k page size? Help needed
« on: January 08, 2021, 04:47:38 pm »
We had some discussions in fedora-devel about changing the default page size from 64k back to 4k

This could be done for Fedora 34 - I opened a change request under Fedora policy

How do people feel about this?

Does anybody want to take ownership of the Fedora change request?

Technically, only one line of code needs to change but there is some coordination to make sure everything in userland is rebuilt and to do some tests of the installer as a bare minimum.

Code: [Select]
CONFIG_PPC_64K_PAGES=n

I might be willing to take ownership of the change personally but if somebody else wants to take ownership, that will free up some of my time for other things.

It is also important to verify that other users are comfortable with this strategy: please feel free to comment through the Fedora mailing list.
« Last Edit: February 16, 2021, 03:31:58 pm by pocock »
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ClassicHasClass

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Re: Fedora 34: going to 4k page size? Help needed
« Reply #1 on: January 08, 2021, 05:12:28 pm »
I see sharkcz is already involved in this conversation. I personally am not aware of anything that would break as a result (in fact, as you correctly point out, many things would suddenly "just work"). My only hesitancy is it would make 64K page kernels more of a pariah than they are already, sort of like another situation with big-endian, and there are performance reasons for 64K pages. Might this, perhaps, be a Workstation-only change and keep the performance benefits for Fedora Server?

pocock

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Re: Fedora 34: going to 4k page size? Help needed
« Reply #2 on: January 08, 2021, 05:35:40 pm »
I already asked this question in the same Fedora thread and it was answered there.  It looks like an extra hassle for them but maybe they can be persuaded, after all, IBM now owns Red Hat.

The page size issue impacts multiple architectures, not only ppc64el.  If proponents of bigger page sizes are willing to invest in resolving it, there are developers who will step up to help and there are tools we can use to detect signs of these problems.  It is a bit like Covid contact tracing, if the right people act with the right tools, we can solve it but we also have other battles to fight too.
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MauryG5

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Re: Fedora 34: going to 4k page size? Help needed
« Reply #3 on: January 09, 2021, 04:00:25 am »
Hi Pocock, I saw your post you tell Fedora developers about this issue that has been around for us for some time now, but do you think we could finally fix this damn crash problem on Navi 10?  You seem to have been supporting this for some time now, as you have seen I think, I was able to start Debian with Wayland's carelessness and the new firmware which obviously was only a Debian problem, but on Fedora we still have to evaluate.  I am trying to modify the Kernel but I noticed that the Fedora one, downloaded from their handouts and therefore official, does not allow to decompress and therefore I cannot try to enter to change the page size and do a test accordingly, then also disabling  Wayland ...

pocock

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Re: Fedora 34: going to 4k page size? Help needed
« Reply #4 on: January 09, 2021, 07:18:43 am »
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MauryG5

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Re: Fedora 34: going to 4k page size? Help needed
« Reply #5 on: January 12, 2021, 12:13:26 pm »
Good evening guys, I'm writing to you from my Power system with Fedora and Kernel 5.9.16! I am sending you the photos of the screen shot just taken. I don't know exactly how he did to load the Kernel because the procedure I had done last time, I was not able to complete it completely and I actually wanted to go back to making some changes but it is also true that I was able to compile before and then install the various modules. It only gave me an error in the "make install" command. But today restarting to see if I could complete the installation, I realized that the Kernel 5.916 made by me, was in plain sight in the list of Fedora Kernels. From what I saw at first boot, the Kernel behaves in a very similar way to the modified one on Debian, that made me install my friend Pocock and therefore the flaw he gives me about that I see in this. If for some reason, he puts himself on a black screen, like that he goes into energy saving or you are without a screen saver and he turns off the montitor after a set time, the system freezes and does not even let me use the monitor options in fact and I have to restart. If I use the computer regularly then it seems to work fine. This flaw also affects the moment it finishes loading the operating system, both Fedora now and Debian with 5.9.6. The moment it finishes loading and the screen would like to move to GPU mode, the screen turns black and has the same identical block and this does it with both Debian and Fedora, so I have to move the video output to where I have the GPU before he goes to black screen and at that point he works. So I think there is some flaw in these new 5.9.X Kernels, regarding this particular. Having said that, the changes I made in this Kernel were, CPU selection which by default from Power 8, I changed it to Power 9, I changed the famous page size from 64K to 4K, as I guessed l 'friend Pocock. The rest I left everything by default. Wayland is active, so the problem at this point seems to be the size of the page ... Pocock thanks for everything you do, you helped me a lot to understand many things that I hope you and others will need ... I am sending you photos of the result of my work ...


tle

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Re: Fedora 34: going to 4k page size? Help needed
« Reply #6 on: January 21, 2021, 06:29:13 am »
 ;D I can confirm my AMD Radeon R9 now runs again on kernel 5.10.7 (4K page sizes).
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MauryG5

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Re: Fedora 34: going to 4k page size? Help needed
« Reply #7 on: January 21, 2021, 07:27:23 am »
Great job TLE, now you too have seen that the problem is only page size.  Can you tell me all the packages you installed on Fedora before doing the Kernel build and installation procedure?  Thanks

tle

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Re: Fedora 34: going to 4k page size? Help needed
« Reply #8 on: January 21, 2021, 10:52:56 pm »
 I follow the instructions in the Fedora wiki page to get the `fepkg` CLI run as expected. No magic here at all
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MauryG5

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Re: Fedora 34: going to 4k page size? Help needed
« Reply #9 on: January 22, 2021, 01:21:39 am »
I ask you because the wiki procedure has never worked for me.  I have installed the packages it asks me but giving the commands then nothing works.  I use the universal procedure that is after having compiled the Kernel, I use in sequence: make -j, make modules_install and make install.  It just doesn't work well on Fedora because some specific package seems to be missing ...

tle

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Re: Fedora 34: going to 4k page size? Help needed
« Reply #10 on: January 22, 2021, 07:46:49 am »
What error did you run into when you run `fedpkg local`. Have you made changes in `kernel-local` and `kernel.spec` file?
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MauryG5

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Re: Fedora 34: going to 4k page size? Help needed
« Reply #11 on: January 22, 2021, 08:18:03 am »
No I have not made any changes.  Are 2 items to change in the compilation do you mean?  I only changed those 2 items I was talking about in the other post, other I have not changed ... let me understand better then how to set these 2 options ... thanks

tle

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Re: Fedora 34: going to 4k page size? Help needed
« Reply #12 on: January 23, 2021, 07:32:07 am »
Regardless of those 2 aforementioned changes, `fedpkg local` should run fine. I could try to help if you could tell me where you get stuck and what errors are
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MauryG5

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Re: Fedora 34: going to 4k page size? Help needed
« Reply #13 on: January 23, 2021, 08:12:59 am »
ok thanks, I have just downloaded the new stable version of the Kernel, 5.10.9, as soon as possible I will try to do the procedure again, I have installed some other packages, when the error comes out I post the output and show you where it stops ... Time to do everything and I send it ...
Thanks for your availability in the meantime!

MauryG5

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Re: Fedora 34: going to 4k page size? Help needed
« Reply #14 on: January 23, 2021, 03:14:02 pm »
TLE here is the error Fedora gives me when I try to do Kernel compilation. After making the changes with "make menuconfig" I execute make -j and press enter.It performs the compilation but when it seems to be finished, it gives this error, what do you think is due to? What correction should be made?
Thanks