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authorChristian Krinitsin <mail@krinitsin.com>2025-06-03 12:04:13 +0000
committerChristian Krinitsin <mail@krinitsin.com>2025-06-03 12:04:13 +0000
commit256709d2eb3fd80d768a99964be5caa61effa2a0 (patch)
tree05b2352fba70923126836a64b6a0de43902e976a /results/classifier/105/boot/2183
parent2ab14fa96a6c5484b5e4ba8337551bb8dcc79cc5 (diff)
downloademulator-bug-study-256709d2eb3fd80d768a99964be5caa61effa2a0.tar.gz
emulator-bug-study-256709d2eb3fd80d768a99964be5caa61effa2a0.zip
add new classifier result
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diff --git a/results/classifier/105/boot/2183 b/results/classifier/105/boot/2183
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+boot: 0.916
+instruction: 0.852
+graphic: 0.830
+device: 0.789
+semantic: 0.758
+other: 0.505
+vnc: 0.499
+socket: 0.431
+network: 0.298
+KVM: 0.251
+assembly: 0.145
+mistranslation: 0.116
+
+aarch-64 emulation much slower since release 8.1.5 (issue also present on 8.2.1)
+Description of problem:
+Since QEMU 8.1.5 our aarch64 based emulation got much slower. We use a linux 5.4 kernel which we cross-compile with the ARM toolchain. Things that are noticable:
+- Boot time got a lot longer
+- All memory accesses seem to take 3x longer (can be verified by e.g. executing below script, address does not matter):
+```
+date
+for i in $(seq 0 1000); do
+ devmem 0x200000000 2>/dev/null
+done
+date
+```
+Steps to reproduce:
+Just boot an ARM based kernel on the virt machine and execute above script.
+Additional information:
+I've tried reproducing the issue on the master branch. There the issue is not present. It only seems to be present on releases 8.1.5 and 8.2.1.
+
+I've narrowed the problem down to following commit on the 8.2 branch (@bonzini): ef74024b76bf285e247add8538c11cb3c7399a1a accel/tcg: Revert mapping of PCREL translation block to multiple virtual addresses.
+
+Let me know if any other information / tests are required.