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| author | Christian Krinitsin <mail@krinitsin.com> | 2025-05-21 21:21:26 +0200 |
|---|---|---|
| committer | Christian Krinitsin <mail@krinitsin.com> | 2025-05-21 21:21:26 +0200 |
| commit | 4b927bc37359dec23f67d3427fc982945f24f404 (patch) | |
| tree | 245449ef9146942dc7fffd0235b48b7e70a00bf2 /gitlab/issues/target_arm/host_arm/accel_missing/1857.toml | |
| parent | aa8bd79cec7bf6790ddb01d156c2ef2201abbaab (diff) | |
| download | qemu-analysis-4b927bc37359dec23f67d3427fc982945f24f404.tar.gz qemu-analysis-4b927bc37359dec23f67d3427fc982945f24f404.zip | |
add gitlab issues in toml format
Diffstat (limited to 'gitlab/issues/target_arm/host_arm/accel_missing/1857.toml')
| -rw-r--r-- | gitlab/issues/target_arm/host_arm/accel_missing/1857.toml | 60 |
1 files changed, 60 insertions, 0 deletions
diff --git a/gitlab/issues/target_arm/host_arm/accel_missing/1857.toml b/gitlab/issues/target_arm/host_arm/accel_missing/1857.toml new file mode 100644 index 000000000..57effb592 --- /dev/null +++ b/gitlab/issues/target_arm/host_arm/accel_missing/1857.toml @@ -0,0 +1,60 @@ +id = 1857 +title = "Major qemu-aarch64 performance slowdown since commit 59b6b42cd3" +state = "closed" +created_at = "2023-09-01T14:00:23.709Z" +closed_at = "2023-09-01T15:15:06.829Z" +labels = ["host: arm", "host: loongarch64", "target: arm"] +url = "https://gitlab.com/qemu-project/qemu/-/issues/1857" +host-os = "Gentoo Linux & Ubuntu & Debian" +host-arch = "loongarch64 & aarch64 & x86_64" +qemu-version = "8.0.0, 8.1.0 and master" +guest-os = "Linux user" +guest-arch = "AArch64" +description = """I have observed a major performance slowdown between qemu 8.0.0 and 8.1.0: + + +qemu 8.0.0: 0.8s + +qemu 8.1.0: 6.8s + + +After bisecting the commits between 8.0.0 and 8.1.0, the offending commit is 59b6b42cd3: + + +commit 59b6b42cd3446862567637f3a7ab31d69c9bef51 +Author: Richard Henderson <richard.henderson@linaro.org> +Date: Tue Jun 6 10:19:39 2023 +0100 + + target/arm: Enable FEAT_LSE2 for -cpu max + + Reviewed-by: Peter Maydell <peter.maydell@linaro.org> + Signed-off-by: Richard Henderson <richard.henderson@linaro.org> + Message-id: 20230530191438.411344-21-richard.henderson@linaro.org + Signed-off-by: Peter Maydell <peter.maydell@linaro.org> + + +Reverting the commit in latest master fixes the problem: + +qemu 8.0.0: 0.8s + +qemu 8.1.0: 6.8s + +qemu master + revert 59b6b42cd3: 0.8s + +Alternatively, specify `-cpu cortex-a35` to disable LSE2: + +`time ./qemu-aarch64 -cpu cortex-a35`: 0.8s + +`time ./qemu-aarch64`: 6.77s + +The slowdown is also observed when running qemu-aarch64 on aarch64 machine: + +`time ./qemu-aarch64 /usr/bin/node -e 1`: 2.91s + +`time ./qemu-aarch64 -cpu cortex-a35 /usr/bin/node -e 1`: 1.77s + +The slowdown on x86_64 machine is small: 362ms -> 378ms.""" +reproduce = """1. Run `time ./qemu-aarch64 node-aarch64 -e 1` (node-aarch64 is NodeJS v16 built for AArch64) +2. Using qemu master, the output says `0.8s` +3. Using qemu master with commit 59b6b42cd3 reverted, the output says `6.77s`""" +additional = """""" |