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Diffstat (limited to 'results/classifier/accel-gemma3:12b/kvm/1790460')
| -rw-r--r-- | results/classifier/accel-gemma3:12b/kvm/1790460 | 26 |
1 files changed, 26 insertions, 0 deletions
diff --git a/results/classifier/accel-gemma3:12b/kvm/1790460 b/results/classifier/accel-gemma3:12b/kvm/1790460 new file mode 100644 index 00000000..4d109d4f --- /dev/null +++ b/results/classifier/accel-gemma3:12b/kvm/1790460 @@ -0,0 +1,26 @@ + +-icount,sleep=off mode is broken (target slows down or hangs) + +QEMU running with options "-icount,sleep=off -rtc clock=vm" doesn't execute emulation at maximum possible speed. +Target virtual clock may run faster or slower than realtime clock by N times, where N value depends on various unrelated conditions (i.e. random from the user point of view). The worst case is when target hangs (hopefully, early in booting stage). +Example scenarios I've described here: http://lists.nongnu.org/archive/html/qemu-discuss/2018-08/msg00102.html + +QEMU process just sleeps most of the time (polling, waiting some condition, etc.). I've tried to debug issue and came to 99% conclusion that there are racing somewhere in qemu internals. + +The feature is broken since v2.6.0 release. +Bad commit is 281b2201e4e18d5b9a26e1e8d81b62b5581a13be by Pavel Dovgalyuk, 03/10/2016 05:56 PM: + + icount: remove obsolete warp call + + qemu_clock_warp call in qemu_tcg_wait_io_event function is not needed + anymore, because it is called in every iteration of main_loop_wait. + + Reviewed-by: Paolo Bonzini <email address hidden> + + Signed-off-by: Pavel Dovgalyuk <email address hidden> + Message-Id: <20160310115603.4812.67559.stgit@PASHA-ISP> + Signed-off-by: Paolo Bonzini <email address hidden> + +I've reverted commit to all major releases and latest git master branch. Issue was fixed for all of them. My adaptation is trivial: just restoring removed function call before "qemu_cond_wait(...)" line. + +I'm sure following bugs are just particular cases of the issue: #1774677, #1653063 . \ No newline at end of file |