Hi Nikolaos > -----Original Message----- > From: POLYCHRONOU Nikolaos via gem5-users <gem5-users@gem5.org> > Sent: 18 November 2020 07:20 > To: gem5-users@gem5.org > Cc: POLYCHRONOU Nikolaos <nikolaos.polychro...@cea.fr> > Subject: [gem5-users] Re: Using perf_event with the ARM PMU inside gem5 on > Linux > > Helllo. > > I encounter the following problem when I try to simulate the starter_fs.py in > aarch64. > > Following these following posts https://www.mail-archive.com/gem5- > us...@gem5.org/msg18401.html <https://www.mail-archive.com/gem5- > us...@gem5.org/msg18401.html> & > https://stackoverflow.com/questions/63988672/using-perf-event-with-the- > arm-pmu-inside-gem5 <https://stackoverflow.com/questions/63988672/using- > perf-event-with-the-arm-pmu-inside-gem5> > > I did the steps to apply the patch and changes and also instantiate the > pmus. I > write a script in the image to access directly the registers. > That's great, I can see Pierre documented really well his work. Which branch are you using? Just so you know, all required patches are now merged into develop and will be part of next Release (gem5v21).
When you say you are accessing the registers directly, do you mean you are adding some inline Assembly to manually initialize the PMU? Or are you relying on the perf_events APIs (which is basically a syscall)? > I manage to read all the events except the cycle counter which always return > 0. > I try to read the cycle counter by instantiating a pmu event counter with 0x11 > but as reading from the ccnt it didn't work as well. > If you are manually accessing the PMU via inline assembly (MSR/MRS), it might be that you are not correctly initializing The cycle counter. The following article explains how to access/initialize the PMU either manually or via perf_event_open http://zhiyisun.github.io/2016/03/02/How-to-Use-Performance-Monitor-Unit-(PMU)-of-64-bit-ARMv8-A-in-Linux.html You can debug what is going on by - Checking gem5 warnings in stdout/stderr - Using the PMUVerbose debug flag - Using gdb and put a breakpoint on any PMU read/write to understand what is going on. > How GEM5 increments this counter. Are the steps to read it the same as in a > real platform or the simulator has a mismatch configuration? > > Also the values obtained reading the counters are not exactly the same as the > m5 resetstats - m5 dumpstats. I guess maybe these two are syscalls as I read . > Which stats / event counters are different? > Another question is how to add the other events that are not implemented. I > tried to do the following in the ArmPMU.py but it didn't work despite seeing > the events created in the console they return 0 values. > > self.addEvent(ProbeEvent(self,0x01,icache,"L1I_CACHE_REFILL")) > > > > self.addEvent(ProbeEvent(self,0x0D, bpred, "BR_IMMED_RETIRED")) > > > > Probably you need to add some counters in the component? Or are the > implemented and I do sth wrong? > > Have you defined a probe point in the icache/bpred? You should instantiate a pmuProbePoint in those classes; those will automatically notify the PMU probe listener if wired correctly. > > Really want some guidance. > > Thank you > > > > > > > > > > > > > > > > > > > > > > > > > > Nikolaos Foivos POLYCHRONOU > > PhD Student - Security of Embedded Systems/IoT/IIoT > > Département DSYS / LSOSP > > > > 17, rue des martyrs | 38000 Grenoble > > Fix work . +33 4 38 78 19 58 > > Office Bat. 4022 - P. 221 > > nikolaos.polychro...@cea.fr > > > > LETI, technology research institute > > Commissariat à l'énergie atomique et aux énergies alternatives > > www.leti.fr <http://www.leti.fr/> | LETI is a member of the Carnot > Institutes > network > > > > > > > > <https://www.youtube.com/channel/UC3JgudJblGykrECv6OUhWFg> > <https://twitter.com/cea_leti> <https://www.linkedin.com/company/leti> > > > > > > IMPORTANT NOTICE: The contents of this email and any attachments are confidential and may also be privileged. If you are not the intended recipient, please notify the sender immediately and do not disclose the contents to any other person, use it for any purpose, or store or copy the information in any medium. Thank you. _______________________________________________ gem5-users mailing list -- gem5-users@gem5.org To unsubscribe send an email to gem5-users-le...@gem5.org %(web_page_url)slistinfo%(cgiext)s/%(_internal_name)s
