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I can't interpret these lines of 'journalctl -b' well:
kernel: pci 0000:02:00.0: 63.012 Gb/s available PCIe bandwidth, limited by 16 GT/s x4 link at 0000:00:01.2 (capable of 126.024 Gb/s with 16 GT/s x8 link)
[...]
kernel: pci 0000:07:00.0: 63.012 Gb/s available PCIe bandwidth, limited by 16 GT/s x4 link at 0000:00:01.2 (capable of 252.048 Gb/s with 16 GT/s x16 link)
[...]
kernel: pci 0000:08:00.0: 63.012 Gb/s available PCIe bandwidth, limited by 16 GT/s x4 link at 0000:00:01.2 (capable of 252.048 Gb/s with 16 GT/s x16 link)
[...]
kernel: pci 0000:09:00.0: 63.012 Gb/s available PCIe bandwidth, limited by 16 GT/s x4 link at 0000:00:01.2 (capable of 252.048 Gb/s with 16 GT/s x16 link)
My PCI cards are as follows:
01:00.0 Non-Volatile memory controller: Samsung Electronics Co Ltd NVMe SSD Controller SM981/PM981/PM983 (PCIe 3.0)
04:00.0 Non-Volatile memory controller: Micron/Crucial Technology P1 NVMe PCIe SSD (rev 03) (PCIe 3.0)
0c:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Navi 10 [Radeon RX 5700 / 5700 XT] (rev c1) (PCIe 4.0) My system consists of Asus Tuf x570; AMD Ryzen 3700x; the two nvme SSDs and the powercolor rx 5700 xt.
That the two NVMe SSDs are 4-line (x4) comes back to me; but that the graphics card (x16) goes to x4 (moreover it's PCIe 4.0) I don't understand. Is this normal, in your opinion?
I leave the links to the complete 'journal' and to complete 'lspci':
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I don't know if this is it, but from your journal:
63.012 Gb/s available PCIe bandwidth, limited by 16 GT/s x4 link at 0000:00:01.2 (capable of 252.048 Gb/s with 16 GT/s x16 link)
and from lspci:
00:01.2 PCI bridge: Advanced Micro Devices, Inc. [AMD] Starship/Matisse GPP Bridge
Search in your motherboard manual; maybe you have some pcie limiting option enabled in bios (or other limiting option)?
Also you may check if there is newer stable bios for your motherboard.
Do you have any performance/stability problems with this system?
Last edited by xerxes_ (2019-12-15 11:23:38)
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I would suggest using lstopo from the hwloc package to help visualize the device connections.
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The only entry I find in Bios is under "Onboard Devices Configuration" where you can set the type of PCIe. From all over "auto" I tried to put "PCIe3" for SSDs and "PCIe4" for Radeon. Nothing has changed.
The bios is up to date and I haven't done any tests. I don't have any games installed because I'm interested in using Blender and Davinci Resolve with OpenCL; but the amdgpu-pro drivers don't work and I'm waiting for the new release. Meanwhile I use amdgpu with mesa-git and llvm-git (but no openCL). I don't know what test to do; do I have to install a game?
Never used "lstopo." I tried with the option "--whole-io" and got the following picture. Does it say anything to you? I don't know how to interpret it.
lstopo
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I interpret it as the following:
kernel: pci 0000:02:00.0: 63.012 Gb/s available PCIe bandwidth, limited by 16 GT/s x4 link at 0000:00:01.2 (capable of 126.024 Gb/s with 16 GT/s x8 link)Empty slot
kernel: pci 0000:07:00.0: 63.012 Gb/s available PCIe bandwidth, limited by 16 GT/s x4 link at 0000:00:01.2 (capable of 252.048 Gb/s with 16 GT/s x16 link)Empty slot
kernel: pci 0000:08:00.0: 63.012 Gb/s available PCIe bandwidth, limited by 16 GT/s x4 link at 0000:00:01.2 (capable of 252.048 Gb/s with 16 GT/s x16 link)Empty slot
kernel: pci 0000:09:00.0: 63.012 Gb/s available PCIe bandwidth, limited by 16 GT/s x4 link at 0000:00:01.2 (capable of 252.048 Gb/s with 16 GT/s x16 link)sda
Edit:
I think the x4 link at 0000:00:01.2 is the x4 link between the CPU and the X570 chipset.
Last edited by loqs (2019-12-15 19:40:22)
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The motherboard has 4 PCIe slots. The only one occupied is the 'PCIe 4.0/3.0 x16_1' which connects the radeon. So the 4 journal entries that are reported do not concern this slot? Another doubt is that 000:09:00.0 contains sda (a crucial mx500 SATA). But what does it have to do with PCIe?
From the image of lstopo you can see that the graphics card (0000:0c:00.0) has two values 4.0 and then after that it returns to be 32 as in almost all other devices. Will this be the limiting factor? (I'm talking at random because I don't know what these values mean)
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See https://imgur.com/a/b7tntpZ block diagram
The 5700 is connected to PCIe4*16 supplied by the CPU.
1 x M.2 PCIe4*4 supplied by the CPU. (nvme0?)
The empty PCIe*16 slot is PCIe*4 electrically supplied by the X570 chipset which only has a PCI4*4 link to the CPU and is also use by all of the following:
The three PCIe 4.0 x1 slots
1 x M.2 PCIe4*4 supplied by the X570. (nvme1?)
wlp5s0
enp6s0
8 SATA ports provided by the X570 also use PCIe
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Thanks for the clarification. I do not know whether to put [Solved] because in the end it turned out to be a false problem. The slots mentioned in the journal are either empty or rightly go to x4 (with the SATA SSD). So there is no limitation.
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