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gem5: fix vs qemu description formating

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Ciro Santilli
2018-05-25 15:54:32 +01:00
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README.adoc
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@@ -4768,16 +4768,22 @@ Like QEMU, gem5 also has a syscall emulation mode (SE), but in this tutorial we
* advantages of gem5: * advantages of gem5:
** simulates a generic more realistic pipelined and optionally out of order CPU cycle by cycle, including a realistic DRAM memory access model with latencies, caches and page table manipulations. This allows us to: ** simulates a generic more realistic pipelined and optionally out of order CPU cycle by cycle, including a realistic DRAM memory access model with latencies, caches and page table manipulations. This allows us to:
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*** do much more realistic performance benchmarking with it, which makes absolutely no sense in QEMU, which is purely functional *** do much more realistic performance benchmarking with it, which makes absolutely no sense in QEMU, which is purely functional
*** make certain functional observations that are not possible in QEMU, e.g.: *** make certain functional observations that are not possible in QEMU, e.g.:
**** use Linux kernel APIs that flush cache memory like DMA, which are crucial for driver development. In QEMU, the driver would still work even if we forget to flush caches. **** use Linux kernel APIs that flush cache memory like DMA, which are crucial for driver development. In QEMU, the driver would still work even if we forget to flush caches.
**** spectre / meltdown: **** spectre / meltdown:
***** https://www.mail-archive.com/gem5-users@gem5.org/msg15319.html ***** https://www.mail-archive.com/gem5-users@gem5.org/msg15319.html
***** https://github.com/jlpresearch/gem5/tree/spectre-test ***** https://github.com/jlpresearch/gem5/tree/spectre-test
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It is not of course truly cycle accurate, as that It is not of course truly cycle accurate, as that:
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** would require exposing proprietary information of the CPU designs: link:https://stackoverflow.com/questions/17454955/can-you-check-performance-of-a-program-running-with-qemu-simulator/33580850#33580850[] ** would require exposing proprietary information of the CPU designs: link:https://stackoverflow.com/questions/17454955/can-you-check-performance-of-a-program-running-with-qemu-simulator/33580850#33580850[]
** would make the simulation even slower TODO confirm, by how much ** would make the simulation even slower TODO confirm, by how much
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but the approximation is reasonable. but the approximation is reasonable.
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