qemu-system-i386 runs slow after upgrading legacy project from qemu 2.9.0 to 7.1.0
Host environment
- Ubuntu 20.04
- OS/kernel version: 5.14
- Architecture: x86_64
- QEMU flavor: qemu-system-i386
- QEMU version: 2.9.0/7.1.0
Emulated/Virtualized environment
- Operating system: freedos
- Architecture: i386
Description of problem
Using several custom serial and irq devices including timers. The same code (after some customisation in order to compile with new 7.1.0 API and meson build system runs about 50% slower. We had to remove "-icount 4" switch which worked fine with 2.9.0 just to get to this point. Even running with multi-threaded tcg did not help. We don't use the new ptimer API but rather the old QEMUTimer. Any suggestions to why we encounter this vast performance degradation?