I’ve observed what looks to be some disk-access-related bottlenecking. In particular, running a speedtest from either Chrome or Firefox within XFCE attempts to murder the CPU. I see it pegging to 95+ percent, and the speed test results are inconsistent and unusable–they’re far too low, likely because the CPU chokes and can’t keep transcieving data fast enough to give an accurate reading.
tl;dr: I want to take my current boot disk (a microSD) and plug it into the USB 3.0 card reader, so I can get its full speed. Do I have to do anything in software to make that happen, or will the Pi manage to find it even though it’s in a different slot?
More info about why I’m doing this and what equipment I’m using:
Card Reader: > https://www.amazon.com/gp/product/B00VAGX6MW/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
Kingston Digital USB 3.0 Super Speed Multi-Card Reader for SD/SDHC/SDXC/microSD/MS/Compact Flash CF Cards (FCR-HS4), White, Brushed Nickel
Current Boot Drive:
Samsung 256GB 100MB/s (U3) MicroSDXC EVO Select Memory Card
Constrained to ~40MB/s in RPi4b microSD
USB 3.0 Attached Card Reader
Test Drive: https://www.amazon.com/Samsung-Class-Adapter-MB-MC64DA-AM/dp/B01273JZMG/ref=sr_1_3?dchild=1&keywords=64GB+Samsung+EVO+Plus+Micro+SD+Card+(Class+10)&qid=1608945291&s=electronics&sr=1-3
Samsung 64GB Evo Plus Class 10 Micro SDXC 80MB/S (MB-MC64DA/AM)
Observed speed attached to RPi4b: ~70MB/s < 80MB/s
speedtest-cli uses about 25-50 percent of the CPU when it’s running the test. With XFCE and Chromium or Firefox open, there’s just nothing left when I try to run the test at speediest.net or fast.com, and I actually start seeing swap space used, and the test reports about half the speed the command line version does. I’ve never seen swap space used without XFCE running.