[BUG] Extreme lag in FreeBSD 2.1.x

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win2kgamer
Posts: 52
Joined: Sun 09 Nov, 2014 12:24 am

[BUG] Extreme lag in FreeBSD 2.1.x

Post by win2kgamer » Fri 13 Mar, 2020 4:38 am

In PCem v15 as well as PCem-dev commit 6bd1c70, FreeBSD 2.1.x lags/appears to hang after hardware probing. This only occurs on Pentium motherboards (The Intel Advanced/ZP and Shuttle HOT-557 were tested):
FreeBSD21_PCemv16.png
FreeBSD21_PCemv16.png (63.37 KiB) Viewed 1056 times
PCem hardware configuration (v15/dev - broken):
Machine: [Socket 7] Shuttle HOT-557
CPU: Intel Pentium 133
Memory: 16MB
Video: Phoenix S3 Trio64
HDD: 800MB IDE
FDD: 3.5" 1.44MB
CD-ROM: 4x PCemCD
Mouse: PS/2 (Microsoft 2-button serial was also tested)

PCem hardware configuration (v15/dev - working):
Machine [486] Award SiS 496/497
CPU: Intel 486DX4/100 (Recompiler enabled)
Memory: 16MB
Video: Phoenix S3 Trio64
HDD: 800MB IDE
FDD: 3.5" 1.44MB
CD-ROM: 4x PCemCD
Mouse: Microsoft 2-button serial

PCem hardware configuration (v14 - working):
Machine: [Socket 7] Award 430VX PCI
CPU: Intel Pentium 133
Memory: 16MB
Video: Phoenix S3 Trio64
HDD: 800MB IDE
FDD: 3.5" 1.44MB
CD-ROM: 4x
Mouse: PS/2

The "hang"/extreme lag occurs around this point in the kernel init/hardware probing:
Screenshot from 2020-03-12 23-32-58.png
Screenshot from 2020-03-12 23-32-58.png (9.62 KiB) Viewed 1056 times
Screenshot from 2020-03-12 23-33-12.png
Screenshot from 2020-03-12 23-33-12.png (11.31 KiB) Viewed 1056 times
Screenshot from 2020-03-12 23-33-18.png
Screenshot from 2020-03-12 23-33-18.png (10.15 KiB) Viewed 1056 times
EDIT: The IDE probe seems to work better in v14:
Screenshot from 2020-03-12 23-42-20.png
Screenshot from 2020-03-12 23-42-20.png (10.7 KiB) Viewed 1055 times
Performance stats when using the SiS 496/497:
FreeBSD21_PCemv16-working.png
FreeBSD21_PCemv16-working.png (59.02 KiB) Viewed 1055 times
EDIT: Updated title as I tested other 2.1.x versions (2.1.5, 2.1.6 and 2.1.7.1) and all of the 2.1 series is affected by this issue. 2.0.x and 2.2.x are not affected.

win2kgamer
Posts: 52
Joined: Sun 09 Nov, 2014 12:24 am

Re: [BUG] Extreme lag in FreeBSD 2.1.x

Post by win2kgamer » Thu 26 Mar, 2020 6:10 pm

I have performed some additional tests and found that the issue becomes a bit less severe (the keyboard response times are a bit shorter but still measured in seconds) when using the Adaptec AHA-1542 SCSI controller instead of IDE, the Tseng ET4000AX instead of an S3 Trio and disabling IDE in the BIOS.

EDIT: Performed some more tests on v16-dev using the Award SiS 496/497 machine and found that the OS works properly on the i486DX4/100 and Am486DX4/120 but the issue occurs on the Pentium OverDrive/63 and Am5x86/P75 CPUs. In v14, FreeBSD 2.1.x works correctly on all CPUs.

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