MiSTer FPGA Forum

hi to all, I noticed that in psx core games should run from sd card, because I get some lag on animations if I run it on a hdd.....

How is the speed when run games from a nas?¿

thanks

https://misteraddons.com/blogs/news/mis ... d-shootout

LAN (Cable) speed is by a biiiiig margin the fastest on mister vs sd/usb.
I have run everything besides arcade cores and minimig from a 1TB SSD on my Unraid NAS for 2-3 years now, works perfectly fine.

I did have some problem (do not remember what tough) at the start with arcade cores and minimig and moved them back to the sd card and since then i have any inkling to try to change them back to the NAS.

you say nas is faster than sd¿

Yes it is considerably faster.

Which animations are experiencing "lag"? SD and USB may be slow by today's standards but the transfer speeds on the PlayStation's CD-ROM drive (even the later revisions) are glacial by comparison. Even if you increase the drive speed in the core it should still shouldn't hit the upper limits of SD/USB transfer speed.

I play ISS Pro Evolution on PlayStation 1 (soccer game), when rom runs from hdd I get some freeze when I make a goal, doesn´t happen from sd card. in general game got some freezes (1 sec aprox.) when running from hdd.

I test if I can replace the original playstation with mister, one of the test I made was playing from sd card and playing from hdd, on older consoles it doesn´t matter, it´s the same, but on playstation I got freezes when using roms from hdd

lag from a spinning hard disk drive is expected, it has to spin up each time it needs more data after it goes to sleep from inactivity. It's one of the worst options.

aberu wrote: ↑Wed Aug 14, 2024 12:37 am

lag from a spinning hard disk drive is expected, it has to spin up each time it needs more data after it goes to sleep from inactivity. It's one of the worst options.

Depends on the HDD enclosure, some of them sent the drive to sleep after a short time of inactivity others not (or after a much longer period that doesn't matter, because the core accesses the drive in this time anyway). I have all my CD-Games on an external USB-HDD that doesn't spin down so fast and have no problem.

I use a sata to usb adapter with double usb (power), and a 2.5 hdd

also using a single usb => s-ata adapter with a 1TB SSD, works fine for me.

in general games run well, but I notice on that one that is kind of a buffer issue, when I make a goal, maybe it´s that game only, when trying to access to the hdd

grizzly wrote: ↑Tue Aug 13, 2024 8:42 pm

https://misteraddons.com/blogs/news/mis ... d-shootout

LAN (Cable) speed is by a biiiiig margin the fastest on mister vs sd/usb.
I have run everything besides arcade cores and minimig from a 1TB SSD on my Unraid NAS for 2-3 years now, works perfectly fine.

I did have some problem (do not remember what tough) at the start with arcade cores and minimig and moved them back to the sd card and since then i have any inkling to try to change them back to the NAS.

Great work, interesting comparison. Though what you did is measure raw bandwidth and have shown that this is in all cases fast enough to feed cores with the required data.

The latency with which data is delivered is just as important, especially for video games and doubly so for network storage. For all disc based games, that are not loaded entirely in temporary storage or RAM, latency is going to be a factor and NAS is not going to come out on top. I run everything from a NAS and there are definitely cases where it causes delays, i.e. the PSX core pausing because of "Slow CD speed". These moments are rare and very brief, but they do occur when loading over network.

Now I imagine you can configure samba or NFS to minimise this latency and not have it be a problem in practice, but without doing so I'm willing to bet that local storage is the safer option for a delay-free experience.

I get around 9MBps writing to any USB attached device or the internal SD card.

Funny how this should even matter. The PSX original CD drive maxes out at 300KB/sec transfer speed and seek times that makes today's summer children cry. Everything should be able to meet that nowadays by a very wide margin. Even if you were to mount a share from across the internet. You should not notice any difference while playing. Updating things from the Linux side of things is a different matter of course, but the simulated systems shouldn't really notice anything.

Bas wrote: ↑Fri Aug 16, 2024 3:17 pm

The PSX original CD drive maxes out at 300KB/sec transfer speed and seek times that makes today's summer children cry. Everything should be able to meet that nowadays by a very wide margin.

Turns out not to be the case.

Quote from the core's creator:

FPGAzumSpass wrote: ↑Wed Feb 07, 2024 6:38 pm

Unfortunatly external drives via USB will result in increased access times, no matter how fast the drive itself is.
As the PSX core needs CD data in realtime, every random delay can lead to issues.
Therefore I cannot really recommend anything USB based.

Network drives however work fine and SDcard also.

That's a very intriguing statement. If anything, a network adds more latency than something directly attached through USB. This statement would theoretically mean that a USB-stick attached to my NAS in the next room would work better than the same USB-stick attached directly to MiSTer. While this might be true, there's a level of voodoo involved in there that my brain won't swallow without at least some clarification.

Bas wrote: ↑Thu Aug 22, 2024 11:30 am

That's a very intriguing statement. If anything, a network adds more latency than something directly attached through USB. This statement would theoretically mean that a USB-stick attached to my NAS in the next room would work better than the same USB-stick attached directly to MiSTer. While this might be true, there's a level of voodoo involved in there that my brain won't swallow without at least some clarification.

I'm not sure, but I doubt that a USB stick attached to a networked storage device would perform better than the same stick plugged to the MiSTer. I can't confirm it; I would need to set up a RetroNAS system or something similar in order to test it. The text I quoted seems to suggest that the problem is the USB protocol itself.

I can however confirm that using an external drive attached to the MiSTer via USB, even SSD, causes the PSX core to make small pauses, which feel like jitter. I don't have a large enough µSD to hold my collection, though, so I usually don't care, and if it bothers me I copy the image I want to play to the µSD.

We have seen this behavior with the psx core again and again now over the years....

Bandwidth alone is useless if you need realtime data. The PSX core is not reading the CD like a software emulator would do, but instead each sector on its own.
There is a prefetch buffer on the ARM side, but that doesn't help with a random seek.

edit: i thought the comparison by Mister addons would contain latency, but it's only bandwidth.
Not sure someone measured the latency yet. But extreme tests using 8x CD speed with fast seek show it pretty easily which is best

to go more into detail:
each sector has about 6ms of time to be processed. What needs to be done in that time?

• request from the core arrives in HPS/ARM. Depending on what it's currently doing, it cannot be processed immidiatly (0-1ms)
• data sometimes has to be read from the storage (sdcard, NAS, usb HDD, ...)
• in case of chd format, the data has to be unpacked
• data has to be sent to the core (1-2ms)
• core has to copy the data to the target buffer (0.25ms)

As you can see, that leaves about 3 ms for reading the data, which is really not plenty when going over USB to a HDD.

Yes, you could buffer more data and early request after a seek to prepare the HPS side, but such things are currently not implemented.

It's surprising that CD head seek times are so fast. Hearing the head move, one would say that it's frigging slow.

I guess one way of getting rid of the issue for sure would be to add support for 2nd µSD card with a CD image. You could only play one PSX game at a time, though, and you would have to rewrite the card (or have a huge collection of cards) to change the CD, but it would satisfy purists like me

I know it's not in the title, but I've used an SSD for the longest time and never experienced any of these issues on the PlayStation core. Given an SSD has a significantly smaller random access time, I guess this helps to verify FPGAzumspass' latency suggestion?

Me neither. I'm using an external Samsung SSD since a few years on my Mister. Never experienced any CD loading delays/issues or e.g. speech synchronicity problems with the CD console cores.

pgimeno wrote: ↑Tue Sep 03, 2024 11:24 am

It's surprising that CD head seek times are so fast. Hearing the head move, one would say that it's frigging slow.

They are not when the head has to move, but depending if it's close or far from the center, you can reach 5-15 or so different sectors without moving the head and this "seek" time is fast.
However, this can also go backwards and is not cached in this case.

Example: seek for sector 123. The head moves to the area where sectors 120-125 are located.
After sector 123 and 124 are read, the game seeks for 120, which has nearly no cost for the CD, but is before previously fetched data from the HDD.

Sure, it's only rare cases, but that's also what is slow with USB HDDs: rare cases. It's not like it stutters 150 times per second for each sector, but occasionally.