Re: [uml-devel] [PATCH v3] um: Switch clocksource to hrtimers

[Thomas Meyer <thomas@m3y3r.de>]

Am Samstag, den 31.10.2015, 14:54 +0100 schrieb Richard Weinberger:
> On Thu, Oct 29, 2015 at 7:23 AM, Anton Ivanov
> <anton.ivanov@kot-begemot.co.uk> wrote:
> > I got the first patchset to build, it works very well on a single
> > core
> > host or with CPU pinning of the UML - the performance gain is >
> > 25%.
> > 
> > However, I introduced a race somewhere along the way - it crashes
> > UML
> > reliably if you do not pin CPUs.
> 
> How does the crash look like?
> I see also an issue with that patch, after UML has an uptime of a few
> minutes
> a task which does nanosleep() will never wake up.
> 
> [<000000006001a29d>] __switch_to+0x53/0x82
> [<00000000602995d2>] __schedule+0x2f4/0x3f7
> [<0000000060299751>] schedule+0x7c/0x95
> [<000000006029b871>] do_nanosleep+0x8b/0x134
> [<0000000060068a41>] hrtimer_nanosleep+0xb2/0x15a
> [<0000000060068b90>] SyS_nanosleep+0xa7/0xbf
> [<000000006001d492>] handle_syscall+0x6a/0x84
> [<00000000600304a8>] userspace+0x3d8/0x463
> [<000000006001a180>] fork_handler+0x85/0x87
> [<ffffffffffffffff>] 0xffffffffffffffff
> 

Hi, 

is this crash/hang about the "switch clocksource to hrtimers" patch or
about the next patch that improves UBD improvements?



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