Am Samstag, den 31.10.2015, 16:13 +0100 schrieb Richard Weinberger: > Am 31.10.2015 um 16:10 schrieb Thomas Meyer: > > Am Samstag, den 31.10.2015, 14:54 +0100 schrieb Richard Weinberger: > > > On Thu, Oct 29, 2015 at 7:23 AM, Anton Ivanov > > > <anton.iva...@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? > > Whoops. Forgot to mention. "switch clocksource to hrtimers" is the > bad one. > So far I can trigger the issue only by starting UML and waiting some > time. mhh. strange. I didn't see this behaviour on my machine, but my machine is a rare single core system so, likely a race condition while relaying the timer interrupt to the userspace process.
But I'm out of ideas how this could happen! what happens when you send the hanging process a SIGVTALRM signal? does it proceed correctly? > > Thanks, > //richard > ------------------------------------------------------------------------------ _______________________________________________ User-mode-linux-devel mailing list User-mode-linux-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel
