Why is my M.2 SSD so slow?

Question

In my system are two M.2 SSD of the same type (Corsair Force MP600). One for Windows, one for Linux. Copying bigger files on Windows always runs with ~4..5GB/s. Surpassing 5GB/s on larger files - and this is obviously including the NTFS overhead.

Yet, on Linux, even a no-FS sequential read:

# cat /dev/nvme0n1p4 | pv > /dev/null
8.86GiB 0:00:12 [ 535MiB/s]
cat /dev/nvme1n1p1 | pv > /dev/null
71GiB 0:00:07 [ 287MiB/s]

Speed fluctuates between 115MB/s up to 800MB/s while averaging at ~300MB/s. Even any SATA SSD is faster:

# cat /dev/sda | pv > /dev/null
63GiB 0:00:09 [ 511MiB/s]
cat /dev/sdd | pv > /dev/null
63GiB 0:00:08 [ 521MiB/s]

What could possibly be wrong here? Is there a kernel config that I have missed? Any help would be greatly appreciated!

Edit: more system info (from neofetch):

OS: Gentoo Base System release 2.7 x86_64
Kernel: 5.15.11-gentoo-x86_64
CPU: AMD Ryzen Threadripper 3970X (64) @ 3.700GHz
Memory: 89322MiB / 193169MiB

Of course you are aware of the fact that your data is being piped to pv. It might not account for the largest part of the delays however, see https://unix.stackexchange.com/questions/191386/pipe-viewer-progress-monitor-performance-consequence — MC68020, Jan 05 '22 at 10:07
@MC68020 cat /dev/zero| pv > /dev/null averages around 5.5GiB/s. So even if it adds overhead, I think in the realm of the measured 300MiB/s it is not really relevant. — IdleMaster, Jan 05 '22 at 10:55
Well, may I ask you to provide os data for your Linux System, like kernel version, distro you are using. Does the systemlog show any signes of possible failure? Like activate default driver, any strange or not normal messages in the logfiles. Otherwise its hard to say. Sometime controller driver can be picky... — terpentin, Jan 05 '22 at 09:55
No upsetting log entries and dmesg is also absolutely clean. — IdleMaster, Jan 05 '22 at 10:56
Are you copying to NTFS? Old driver has always been slow as it had to be developed without any help from Microsoft and used fuse. The New NTFS File-System Driver Has Been Submitted For Linux 5.15 Sept 2021 https://www.phoronix.com/scan.php?page=news_item&px=NTFS3-For-Linux-5.15 — oldfred, Jan 05 '22 at 14:30
What speed do you get with something like dd with a larger block size pointed at /dev/null? You can send SIGUSR1 to it to get it to print progress and time its operation. — binki, Jan 05 '22 at 14:55
Did you check on lspci and make sure you built support for your specific system? Maybe you’re not enabling the newest version of PCI Express or something. I don’t know what things are called or what to look for. — binki, Jan 05 '22 at 14:58
Do things magically work fast from a livecd or if you use genkernel and kernel modules? — binki, Jan 05 '22 at 14:59
@binki dd if=/dev/nvme0n1 of=/dev/null bs=10M count=2k gives 21 GB, 20 GiB) copied, 48.1178 s, 446 MB/s I will try to boot a live system (maybe a standard Ubuntu) and compare - good idea! — IdleMaster, Jan 05 '22 at 18:50

Why is my M.2 SSD so slow?

cat /dev/nvme1n1p1 | pv > /dev/null

cat /dev/sdd | pv > /dev/null

0 Answers0