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nathanlkoch Apprentice
Joined: 31 Jan 2021 Posts: 163 Location: Earth / Sol
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Posted: Tue Feb 02, 2021 5:12 am Post subject: Gentoo tmpfs on GPU Ram disk? |
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Could one setup distc with portage's directory on a gpu ramdisk for extremely fast builds? Has anyone done it before? |
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DawgG l33t
Joined: 17 Sep 2003 Posts: 874
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Posted: Tue Feb 02, 2021 10:01 am Post subject: |
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it can certainly be done: mount the tmpfs and set portage_tmpdir (look up the exact variable name in make.conf) to that.
i wouldn't expect Quote: | extremely fast builds | though because on systems accessible to us mere mortals usually disk-io or, in this case, ram-speed isn't the limiting factor when compiling but cpu power. i ususally keep portage_tmpdir in ram and i cannot say there is a noticeable speed increase when building. just give it a try!
GOOD LUCK! _________________ DUMM KLICKT GUT. |
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NeddySeagoon Administrator
Joined: 05 Jul 2003 Posts: 54641 Location: 56N 3W
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Posted: Tue Feb 02, 2021 12:07 pm Post subject: |
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DawgG,
There isn't a speed improvement for the portage build space in RAM.
When you have the RAM for it. the kernel virtual memory system keeps the build products in the disk cache. They are never flushed as there is no demand on RAM.
You just get a lot of writes to disk that are never read. Putting the portage build space in RAM saves these writes. That's a good thing on SSD.
It saves bus bandwidth but thats not a speed improvement that you would notice.
As to using the RAM on a GPU, it will be slower than main memory because the interface is not designed to access filesystems. _________________ Regards,
NeddySeagoon
Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail. |
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DawgG l33t
Joined: 17 Sep 2003 Posts: 874
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Posted: Tue Feb 02, 2021 1:16 pm Post subject: |
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NeddySeagoon,
you are right - THX for the info.
one other main reason for doing this is that it "cleans" the build-dir on every remount/reboot. _________________ DUMM KLICKT GUT. |
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Ant P. Watchman
Joined: 18 Apr 2009 Posts: 6920
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Posted: Tue Feb 02, 2021 3:40 pm Post subject: |
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A PCIe 4.0 x16 card will give you a maximum of 31GB/s bandwidth. Dual-channel DDR4 at its slowest rated speed is faster than that. Same goes for PCIe/DDR 3 and most of DDR 2 as well.
You won't get extremely fast builds, you'll get extremely hot builds. |
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nathanlkoch Apprentice
Joined: 31 Jan 2021 Posts: 163 Location: Earth / Sol
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Posted: Tue Feb 02, 2021 7:11 pm Post subject: |
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Now I know. |
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Zucca Moderator
Joined: 14 Jun 2007 Posts: 3776 Location: Rasi, Finland
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Posted: Tue Feb 02, 2021 7:37 pm Post subject: |
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Fun fact: there was a driver that made possible to use GPU ram as swap. It could be useful on some laptops with dedicated gpu. _________________ ..: Zucca :..
My gentoo installs: | init=/sbin/openrc-init
-systemd -logind -elogind seatd |
Quote: | I am NaN! I am a man! |
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nathanlkoch Apprentice
Joined: 31 Jan 2021 Posts: 163 Location: Earth / Sol
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Posted: Tue Feb 02, 2021 9:05 pm Post subject: |
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Zucca wrote: | Fun fact: there was a driver that made possible to use GPU ram as swap. It could be useful on some laptops with dedicated gpu. |
Neat-o. |
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pjp Administrator
Joined: 16 Apr 2002 Posts: 20521
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Posted: Tue Feb 02, 2021 9:12 pm Post subject: |
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Zucca wrote: | Fun fact: there was a driver that made possible to use GPU ram as swap. It could be useful on some laptops with dedicated gpu. | Also to not use system RAM and still preserve solid-state devices. _________________ Quis separabit? Quo animo? |
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nick_gentoo Tux's lil' helper
Joined: 07 Jan 2019 Posts: 140
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Posted: Wed Feb 03, 2021 12:20 pm Post subject: |
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Hi, I understand why the GPU ramdisk is not such a good idea, but the geek in me is asking: HOW exactly is that done? |
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nathanlkoch Apprentice
Joined: 31 Jan 2021 Posts: 163 Location: Earth / Sol
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Zucca Moderator
Joined: 14 Jun 2007 Posts: 3776 Location: Rasi, Finland
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Posted: Wed Feb 03, 2021 8:02 pm Post subject: |
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https://github.com/Overv/vramfs
Oh this is fun. :P _________________ ..: Zucca :..
My gentoo installs: | init=/sbin/openrc-init
-systemd -logind -elogind seatd |
Quote: | I am NaN! I am a man! |
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nick_gentoo Tux's lil' helper
Joined: 07 Jan 2019 Posts: 140
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Posted: Thu Feb 04, 2021 9:49 am Post subject: |
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Thank you for the pointers!
Zucca wrote: | Oh this is fun. |
Yes, indeed |
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Zucca Moderator
Joined: 14 Jun 2007 Posts: 3776 Location: Rasi, Finland
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Posted: Thu Feb 04, 2021 10:29 am Post subject: |
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Now... Do I spare on RAM next time and invest in a pro GPU that has lots of vRAM?
Joking.
A little off-topic, but I have been looking at those WAM (Write acceleration module) cards as a faster swap device. Still buying more RAM makes more sense, obviously. But a PCIe card filled with cheap DDR3 memory is an interesting concept. _________________ ..: Zucca :..
My gentoo installs: | init=/sbin/openrc-init
-systemd -logind -elogind seatd |
Quote: | I am NaN! I am a man! |
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