Hi Shehab, One quick note: There is *no way* to have deterministic behavior when running with KVM. Since you are using the hardware, the underlying host OS will influence the execution path of the workload.
To try to narrow down the bug you're seeing, you can try to take a checkpoint after booting with KVM. Then, the execution from the checkpoint should be deterministic since it is 100% in gem5. BTW, I doubt you can run the KVM CPU in a VM since this would require your hardware and the VM to support nested virtualization. There *is* support for this in the Linux kernel, but I don't think it's been widely deployed outside of specific cloud environments. One other note: Pouya has pushed some changes which implement some x86 instructions that were causing issues for him. You can try with the current gem5 mainline to see if that helps. Cheers, Jason On Fri, Sep 6, 2019 at 8:22 AM Shehab Elsayed <[email protected]> wrote: > That's interesting. Are you using Full System as well? I don't think FS > behavior is supposed to be so dependent on the host environment! > > On Fri, Sep 6, 2019 at 11:16 AM Gambord, Ryan <[email protected]> > wrote: > >> I have found that gem5 behavior is sensitive to the execution >> environment. I now run gem5 inside an ubuntu vm on qemu and have had much >> more consistent results. I haven't tried running kvm gem5 inside a kvm qemu >> vm, so not sure how that works, but might be worth trying. >> >> Ryan >> >> >> On Fri, Sep 6, 2019, 08:07 Shehab Elsayed <[email protected]> wrote: >> >>> I was wondering if anyone is running into the same problem or if anyone >>> has any suggestions on how to proceed with debugging this problem. >>> >>> On Mon, Jul 29, 2019 at 4:57 PM Shehab Elsayed <[email protected]> >>> wrote: >>> >>>> Sorry for the spam. I just forgot to mention that the system >>>> configuration I am using is mainly from >>>> https://github.com/darchr/gem5/tree/jason/kvm-testing/configs/myconfigs. >>>> <https://github.com/darchr/gem5/tree/jason/kvm-testing/configs/myconfigs> >>>> >>>> >>>> Shehab Y. Elsayed, MSc. >>>> PhD Student >>>> The Edwards S. Rogers Sr. Dept. of Electrical and Computer Engineering >>>> University of Toronto >>>> E-mail: [email protected] >>>> <https://webmail.rice.edu/imp/message.php?mailbox=INBOX&index=11#> >>>> >>>> >>>> On Mon, Jul 29, 2019 at 4:08 PM Shehab Elsayed <[email protected]> >>>> wrote: >>>> >>>>> I have set up a repo with gem5 that demonstrates the problem. The repo >>>>> includes the latest version of gem5 from gem5's github repo with a few >>>>> patches applied to get KVM working together with the kernel binary and >>>>> disk >>>>> image I am using. You can get the repo at >>>>> https://github.com/ShehabElsayed/gem5_debug.git. >>>>> <https://github.com/ShehabElsayed/gem5_debug.git> >>>>> >>>>> These steps should reproduce the problem: >>>>> 1- scons build/X86/gem5.opt >>>>> 2- ./scripts/get_fs_stuff.sh >>>>> 3- ./scripts/run_fs.sh 8 >>>>> >>>>> I have also included sample m5term outputs for both a 2 thread run >>>>> (m5out_2t) and an 8 thread run (m5out_8t) >>>>> >>>>> Any help is really appreciated. >>>>> >>>>> >>>>> >>>>> On Tue, Jul 23, 2019 at 11:01 AM Shehab Elsayed <[email protected]> >>>>> wrote: >>>>> >>>>>> When I enable the Exec debug flag I can see that it seems to be stuck >>>>>> in a spin lock (queued_spin_lock_slowpath) >>>>>> >>>>>> On Fri, Jul 19, 2019 at 5:28 PM Shehab Elsayed <[email protected]> >>>>>> wrote: >>>>>> >>>>>>> Hello All, >>>>>>> >>>>>>> I have a gem5 X86 full system set up that starts with KVM cores and >>>>>>> then switches to O3 cores once the benchmark reaches the region of >>>>>>> interest. Right now I am testing with a simple multithreaded hello >>>>>>> world benchmark. Sometimes the benchmark completes successfully while >>>>>>> others gem5 just seems to hang after starting the benchmark. I believe >>>>>>> it >>>>>>> is still executing some instructions but without making any progress. >>>>>>> The >>>>>>> chance of this behavior (indeterminism) happening increases as the >>>>>>> number of simulated cores or the number of threads created by the >>>>>>> benchmark >>>>>>> increases. >>>>>>> >>>>>>> Any ideas what might be the reason for this or how I can start >>>>>>> debugging this problem? >>>>>>> >>>>>>> Note: I have tried the patch in https://gem5-review.googlesource >>>>>>> .com/c/public/gem5/+/19568 but the problem persists. >>>>>>> >>>>>>> Thanks! >>>>>>> >>>>>> _______________________________________________ >>> gem5-users mailing list >>> [email protected] >>> http://m5sim.org/cgi-bin/mailman/listinfo/gem5-users >> >> _______________________________________________ >> gem5-users mailing list >> [email protected] >> http://m5sim.org/cgi-bin/mailman/listinfo/gem5-users > > _______________________________________________ > gem5-users mailing list > [email protected] > http://m5sim.org/cgi-bin/mailman/listinfo/gem5-users
_______________________________________________ gem5-users mailing list [email protected] http://m5sim.org/cgi-bin/mailman/listinfo/gem5-users
