Re: kern/57273: poll timeout is doubled when NetBSD is run inside QEMU

[Paul Goyette <paul%whooppee.com@localhost>]

See kern/43997

On Thu, 16 Mar 2023, roy%marples.name@localhost wrote:

> > Number:         57273
> > Category:       kern
> > Synopsis:       poll timeout is doubled when NetBSD is run inside QEMU
> > Confidential:   no
> > Severity:       serious
> > Priority:       medium
> > Responsible:    kern-bug-people
> > State:          open
> > Class:          sw-bug
> > Submitter-Id:   net
> > Arrival-Date:   Thu Mar 16 16:55:00 +0000 2023
> > Originator:     Roy Marples
> > Release:        NetBSD-9.3
> > Organization:
> > Environment:
> NetBSD netbsd9 9.3_STABLE NetBSD 9.3_STABLE (GENERIC) #0: Mon Mar 13 21:38:46 UTC 2023  mkrepro%mkrepro.NetBSD.org@localhost:/usr/src/sys/arch/amd64/compile/GENERIC amd64
> > Description:
> Testing dhcpcd timings in a NetBSD vm is impossible because the time to sleep with any polling mechanism (poll, pollts, kqueue) is doubled.
> Outside the vm, on bare metal, it works fine.
> > How-To-Repeat:
> Install NetBSD to a qemu VM hosted on NetBSD.
>
> Reproducer:
>
> #include <poll.h>
> #include <stdio.h>
> #include <time.h>
>
> int
> main(void)
> {
>        struct timespec ts = { .tv_sec = 10 };
>        struct timespec start, end;
>
>        fprintf(stderr, "ppoll timeout %ld secs\n", ts.tv_sec);
>        clock_gettime(CLOCK_MONOTONIC, &start);
>        fprintf(stderr, "poll start is %ld, timeout is %ld, end should be %ld\n",
>            start.tv_sec, ts.tv_sec, start.tv_sec + ts.tv_sec);
>        pollts(NULL, 0, &ts, NULL);
>        clock_gettime(CLOCK_MONOTONIC, &end);
>        fprintf(stderr, "poll end is %ld, off by %ld secs\n",
>            end.tv_sec, end.tv_sec - (start.tv_sec + ts.tv_sec));
>        return 0;
> }
> > Fix:
>
>
> !DSPAM:641349ef114062545387549!

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