Hi, I would think that it's OK to ignore the "prefetch_nta is unimplemented" since it should just give hints to the cache. If you don't see *any* other unimplemented instruction warning then I would guess that unimplemented instructions is not the problem.
Another possibility is something is going wrong with checkpoint taking or restoring. Have you tried fast-forwarding with KVM then switching CPUs without taking a checkpoint? If that works when the checkpoint doesn't work then you'll know that it's a problem with checkpointing. Jason On Mon, Jul 16, 2018 at 1:51 PM Da Zhang <[email protected]> wrote: > Hey Jason, > > There are a bunch of "warn: instruction 'prefetch_nta' unimplemented" in > atomic modes, during which the java benchmarks don't crash. However, there > is no these kind of warnings during timing mode. Does it imply that > unimplemented instructions don't cause the problem? Any clues or > suggestions to debug these problems? > > best, > Da Zhang > > > > On Mon, Jul 16, 2018 at 1:32 PM Jason Lowe-Power <[email protected]> > wrote: > >> Hello, >> >> Are you seeing any warnings like "warn: Instruction XXX not implemented"? >> >> There are many X86 SIMD instructions that are currently unimplemented. I >> would bet that your application is using some of those instructions and >> getting 0's as the output instead of the correct value. >> >> The "right" way to solve this problem is to implement these instructions >> (and we would really appreciate it if you contribute your fixes back on >> https://gem5-review.googlesource.com. The other option is to recompile >> your applications without SIMD extensions (e.g., -march=athlon64 or >> whatever is the original x86-64 name in GCC). However, this likely requires >> compiling all of the java runtime in your case. >> >> Cheers, >> Jason >> >> On Mon, Jul 16, 2018 at 10:11 AM Da Zhang <[email protected]> wrote: >> >>> To clarify, "SIGSEGV and null exceptions " happens to the benchmark >>> suite, not gem5. Gem5 is running without errors. But in the >>> system.pc.com_1.device files, I observe that most of the benchmarks crash >>> due to SIGSEGV or null exceptions. >>> Example: >>> " >>> >>> x/system.pc.com_1.device >>> >>> >>> >>> buffers >>> >>> 1 # >>> >>> 2 # A fatal error has been detected by the Java Runtime Environment: >>> >>> 3 # >>> >>> 4 # SIGSEGV (0xb) at pc=0x00007f81d17742b7, pid=1474, >>> tid=0x00007f81cf46d700 >>> >>> 5 # >>> >>> 6 # JRE version: Java(TM) SE Runtime Environment (8.0_171-b11) (build >>> 1.8.0_171-b11) >>> >>> 7 # Java VM: Java HotSpot(TM) 64-Bit Server VM (25.171-b11 mixed mode >>> linux-amd64 compressed oops) >>> >>> 8 # Problematic frame: >>> >>> 9 # J 1815 C2 >>> org.apache.xml.serializer.ToHTMLStream.endElement(Ljava/lang/String;Ljava/lang/String;Ljava/lang/String;)V >>> (389 bytes) @ 0x00007f81d17742b7 [0x00007f81d1774280+0x37] >>> >>> >>> >>> 10 # >>> >>> 11 # >>> " >>> >>> On Mon, Jul 16, 2018 at 11:39 AM Da Zhang <[email protected]> wrote: >>> >>>> Hey guys, >>>> >>>> I am testing a java benchmark suite, dacapo, on gem5 with fs mode. >>>> Unfortunately, I encounter a lot of SIGSEGV and null exceptions during >>>> timing mode after restarting from the checkpoints. >>>> I am using linux kernel v4.8.13 and ubuntu-server-16.04.1 with >>>> oracle jdk v8.0_171-b11. To eliminate the influence of my modifications to >>>> gem5 src/ and configs/, I re-download gem5 and checkout to commit >>>> "ee2ffdc0fdb489767768e5273a4ccd7b51735c7c", which is the gem5 version I am >>>> working on. The checkpoint was taken by using kvm cpu with 1 CPU and 16GB >>>> memory. For the simulation, I use build/X86/gem5.opt (in order to enable >>>> assertions) with fs mode (configs/example/fs.py). Other options include >>>> "--cpu-type=DerivO3CPU -n 1 --mem-size=16GB --caches --l2cache >>>> --l2_size=${L2SIZE}" (I try L2SIZE from 256KB to 8MB). I test with 100ms >>>> warmup and 1ps real simulation time. There are no errors presented. But >>>> with longer real simulation time, the benchmark suite crashes with >>>> segfault. >>>> I am able to run the dacapo benchmark suite in fs mode with kvm cpu, >>>> without any segfaults or exceptions. I have some simple java benchmarks >>>> tested; neither segfaults nor exceptions present. >>>> Does anyone have suggestions or experience against these issues? >>>> >>>> best, >>>> Da Zhang >>>> >>> _______________________________________________ >>> 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
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