[HN Gopher] Faster Linux 2.5G Networking with Realtek RTL8125B
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Faster Linux 2.5G Networking with Realtek RTL8125B
Author : geerlingguy
Score : 36 points
Date : 2021-12-21 20:45 UTC (2 hours ago)
(HTM) web link (www.jeffgeerling.com)
(TXT) w3m dump (www.jeffgeerling.com)
| daneel_w wrote:
| PCI-E cards with this chip cost about $15 today, and 2.5G
| Ethernet switches just over $100. Post-gigabit networking has
| become truly affordable.
| gsich wrote:
| What, where?
| netr0ute wrote:
| > just over $100
|
| This is pretty expensive considering that you can get a 10G
| switch instead for around $40 more.
| makomk wrote:
| Believe it or not, the fact that 2.5G switches are cheaper
| than 10G switches at all is an improvement. There seems to be
| a weird lack of interest in shipping it as a consumer
| technology.
| flemhans wrote:
| Why do Ethernet standards mostly come in 10x orders of
| magnitude, anyway?
|
| 10 -> 100 -> 1000 -> 10G -> 100G
|
| I know there are some oddball 25G, 40G, and 2.5G out there
| too, but always wondered this.
| cedivad wrote:
| Not a copper one though.
| mattst88 wrote:
| I've always been confused by the situation with Realtek Linux
| drivers.
|
| Does anyone know why they are not contributing to the kernel
| directly? (Just a guess: their drivers are from the same codebase
| as the Windows driver and use a bunch of abstraction layers that
| wouldn't be acceptable in Linux)
| KarlKemp wrote:
| Do they publish source code or binary drivers? If it's the
| latter, the article points at why they might not want their
| competitors to read their source code: the drivers matter a
| lot, and starting from theirs might well cut the development
| costs for a competing product in half.
| gsich wrote:
| Source code and no BLOBs.
| morning_gelato wrote:
| Realtek does contribute directly to the kernel, but I think it
| depends on which internal team is handling the device support.
| For their PCIe 802.11ac and 802.11ax wifi cards Realtek devs
| wrote and upstreamed rtw88[1] and rtw89[2] respectively.
|
| [1]
| https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/lin...
|
| [2]
| https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/lin...
| pantalaimon wrote:
| Wasn't rtw88 supposed to abstract away the transport so it
| could be used with PCIe, USB and SDIO? [0] The later two
| never materialized (there is the out of tree rtw88-usb [1]
| but it's not very active and not maintained by Realtek)
|
| [0] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/
| lin...
|
| [1] https://github.com/ulli-kroll/rtw88-usb
| formerly_proven wrote:
| I'm guessing the story is overall similar to how gigabit ethernet
| was ~ten years ago: Use Intel if you want working hardware and
| drivers that actually achieve line-rate throughput. Back then the
| RTL chips were a trashfire and couldn't do gigabit even on
| Windows. Nowadays the RTL chips can do that. And here we are
| again with bad / proprietary _network_ drivers for RTL chips.
| gsich wrote:
| The driver from Realtek is GPL2. Maybe the code quality is not
| good enough for the kernel.
|
| https://www.realtek.com/en/component/zoo/category/network-in...
| my123 wrote:
| They are upstream nowadays.
|
| Supported mainline by the r8169 driver.
| gsich wrote:
| Yeah, but according to the blog post there must be some
| difference. "Supported" but not "fully supported". Mainline
| has 8k lines, Realteks driver has 15k lines in only 1 .c
| file and there are some more.
| my123 wrote:
| For 2.5GbE, this became very much not the case.
|
| > Use Intel if you want working hardware
|
| Sadly Intel totally dropped the ball on this.
|
| i225-V (Foxville) NIC early steppings were awful. And no driver
| can fix that, it required Intel to produce a new stepping...
| countless motherboards are affected by that one...
|
| Realtek NICs are fine at this point in time.
| makomk wrote:
| Yeah, Intel managed to incorrectly implement the 2.5GbE
| standard with the result that if you connected older
| steppings of their NIC to a standards-compliant device
| massive packet loss and effective data transfer speeds
| apparently as low as kilobytes/sec in some cases ensued. The
| only workaround was to force it to gigabit mode. They took an
| age to release a stepping that fixed this and I think there
| may have been other issues too, so a whole bunch of
| motherboards ended up shipping with 2.5Gb support that was
| effectively unusable.
| bcrl wrote:
| Not all Realtek NICs are fine at this point in time. For some
| models of Realtek NIcs the Linux driver has to memcpy() data
| for _every single packet_ in order to work around a hardware
| bug. It 's entirely possible that the Linux driver has that
| kind of workaround enabled for newer hardware that doesn't
| need it anymore, but getting that kind of driver change
| merged tends to be a bit of an uphill battle without having
| the hardware manufacturer actively involved in maintenance of
| the mainline open source driver.
| nightfly wrote:
| Isn't it the same for wifi? On nearly every laptop I've owned
| I've ended up swapping for an Intel wireless card eventually.
| formerly_proven wrote:
| Yes, and even the generational changes can be quite worth it
| - I recently swapped a 2016 Intel 8265 wifi card with a newer
| AX210 (- which costs basically nothing) and even without
| utilizing the updated standards I got 50-80 % more bandwidth
| under exactly the same conditions.
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(page generated 2021-12-21 23:00 UTC)