Periodic several second freezes with Raspberry Pi 3

[arutema]

(06-03-2016 01:16 AM)[Unknown] Wrote:  Deadline is a popular option among flash drives. CFQ is typically the default used with moving-parts disks.

If that affects it, it definitely indicates this is IO latency related. Are you using a cso or iso? How much memory does the device have? Could it be swapping - do you see swap usage?

Do pis come by default with zram configured, or do they use SD card swap, or no swap at all?

-[Unknown]

Pi 3 comes with 1GB of ram, 128M of which has to be reserved for the GPU for PPSSPP, leaving about 860M for the OS and PPSSPP. A swapfile is on the SD card.

Looking at sar -r and sar -R, it looks like these hangs match up to drops in kbdirty, while swap usage stays at 0. I wonder if the default system settings are to flush writeback cache in big chunks to limit write-cycles to the SD card.

This wouldn't affect emulators for cartridge-based systems, since they typically keep the whole ROM image in memory.

I haven't tried PS1 emulation on the Pi 3 yet, but I suspect it may see similar issues. dankcushions, I don't suppose you have any reports from PS1 emulators?

sar excerpts attached. And for reference, all my games are uncompressed ISO or PSN store downloads.