[Qemu-devel] OpenBSD sched_yield() calls increase

[Qemu-devel] OpenBSD sched_yield() calls increase

[Sai Prajeeth]

[-- Attachment #1: Type: text/plain, Size: 734 bytes --]

Hi list,

When running OpenBSD on QEMU without KVM, I see an increase in the number
of sched_yield() system calls in certain multi-threaded benchmarks
(sysbench). However while using KVM accelerator, the number of this system
calls is minimal. Does any have any insight why this is happening? The
execution of the benchmark is really slowed when not using KVM which is to
be expected but why is there such as massive increase in sched_yield system
calls? Moreover when using icount the number of sched_yield calls is
further increased.

Some Number:

With KVM accelerator - #of sched_yields = 500
Using TCG - #of sched_yields = 2600
Using icount - #of sched_yields = 16000

Anyone has an idea why this might be happening?

Thank you!

[-- Attachment #2: Type: text/html, Size: 911 bytes --]