1 files changed, 53 insertions, 0 deletions
diff --git a/results/classifier/118/performance/1672383 b/results/classifier/118/performance/1672383
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+performance: 0.933
+device: 0.519
+PID: 0.517
+x86: 0.489
+ppc: 0.473
+architecture: 0.468
+boot: 0.462
+i386: 0.438
+vnc: 0.421
+graphic: 0.395
+socket: 0.387
+files: 0.385
+network: 0.375
+user-level: 0.363
+peripherals: 0.337
+hypervisor: 0.337
+kernel: 0.331
+TCG: 0.327
+permissions: 0.306
+VMM: 0.285
+semantic: 0.281
+arm: 0.255
+risc-v: 0.254
+register: 0.211
+debug: 0.196
+mistranslation: 0.141
+virtual: 0.135
+assembly: 0.102
+KVM: 0.009
+
+Slow Windows XP load after commit a9353fe897ca2687e5b3385ed39e3db3927a90e0
+
+I've recently discovered, that in QEMU 2.8+ my Windows XP loading time has significantly worsened. In 2.7 it took 30-40 second to boot, but in 2.8 it became 2-2,5 minutes.
+
+I've used Git bisect, and found out that the change happened after commit a9353fe897ca2687e5b3385ed39e3db3927a90e0, which, as far as I can tell from the commit message, handled race condition when invalidating breakpoint.
+
+I've set a breakpoint in static void breakpoint_invalidate(CPUState *cpu, target_ulong pc), and here's a backtrace:
+#0  cpu_breakpoint_insert (cpu=cpu@entry=0x555556a73be0, pc=144, 
+    flags=flags@entry=32, breakpoint=breakpoint@entry=0x555556a7c670)
+    at /media/sdd2/qemu-work/exec.c:830
+#1  0x00005555558746ac in hw_breakpoint_insert (env=env@entry=0x555556a7be60, 
+    index=index@entry=0) at /media/sdd2/qemu-work/target-i386/bpt_helper.c:64
+#2  0x00005555558748ed in cpu_x86_update_dr7 (env=0x555556a7be60, 
+    new_dr7=<optimised out>)
+    at /media/sdd2/qemu-work/target-i386/bpt_helper.c:160
+#3  0x00007fffa17421f6 in code_gen_buffer ()
+#4  0x000055555577fcb4 in cpu_tb_exec (itb=<optimised out>, 
+    itb=<optimised out>, cpu=0x7fff8b7763b0)
+    at /media/sdd2/qemu-work/cpu-exec.c:164
+It seems that XP sets some breakpoints during it's load, and it leads to frequent TB flushes and slow execution.
+
+Supposedly fixed by commit 406bc339b0505fcfc2ffcbca1f05a3756e338a65
+