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From:   "chenxiang (M)" <chenxiang66@hisilicon.com>
Subject: [Bug] Take more 150s to boot qemu on ARM64
To:     <paulmck@kernel.org>
CC:     <linux-kernel@vger.kernel.org>, <qemu-devel@nongnu.org>,
        <linuxarm@huawei.com>
Message-ID: <36a0c658-ee5d-3a1c-416c-c041dc344bff@hisilicon.com>
Date:   Mon, 13 Jun 2022 20:26:34 +0800
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Hi all,

I encounter a issue with kernel 5.19-rc1 on a ARM64 board:  it takes 
about 150s between beginning to run qemu command and beginng to boot 
Linux kernel ("EFI stub: Booting Linux Kernel...").

But in kernel 5.18-rc4, it only takes about 5s. I git bisect the kernel 
code and it finds c2445d387850 ("srcu: Add contention check to 
call_srcu() srcu_data ->lock acquisition").

The qemu (qemu version is 6.2.92) command i run is :

./qemu-system-aarch64 -m 4G,slots=4,maxmem=8g \
--trace "kvm*" \
-cpu host \
-machine virt,accel=kvm,gic-version=3  \
-machine smp.cpus=2,smp.sockets=2 \
-no-reboot \
-nographic \
-monitor unix:/home/cx/qmp-test,server,nowait \
-bios /home/cx/boot/QEMU_EFI.fd \
-kernel /home/cx/boot/Image  \
-device 
pcie-root-port,port=0x8,chassis=1,id=net1,bus=pcie.0,multifunction=on,addr=0x1 
\
-device vfio-pci,host=7d:01.3,id=net0 \
-device virtio-blk-pci,drive=drive0,id=virtblk0,num-queues=4  \
-drive file=/home/cx/boot/boot_ubuntu.img,if=none,id=drive0 \
-append "rdinit=init console=ttyAMA0 root=/dev/vda rootfstype=ext4 rw " \
-net none \
-D /home/cx/qemu_log.txt

I am not familiar with rcu code, and don't know how it causes the issue. 
Do you have any idea about this issue?


Best Regard,

Xiang Chen