From b24bad34bf6017d49724bedd0a428dea0056bbd6 Mon Sep 17 00:00:00 2001 From: Alex Bennée Date: Wed, 23 Oct 2024 12:33:56 +0100 Subject: accel/tcg: add tracepoints for cpu_loop_exit_atomic MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit We try to avoid using cpu_loop_exit_atomic as it brings in an all-core sync point. However on some cpu/kernel/benchmark combinations it is starting to show up in the performance profile. To make it easier to see whats going on add tracepoints for the slow path so we can see what is triggering the wait. It seems for a modern CPU it can be quite a bit, for example: ./qemu-system-aarch64 \ -machine type=virt,virtualization=on,pflash0=rom,pflash1=efivars,gic-version=max \ -smp 4 \ -accel tcg \ -device virtio-net-pci,netdev=unet \ -device virtio-scsi-pci \ -device scsi-hd,drive=hd \ -netdev user,id=unet,hostfwd=tcp::2222-:22 \ -blockdev driver=raw,node-name=hd,file.driver=host_device,file.filename=/dev/zen-ssd2/trixie-arm64,discard=unmap \ -serial mon:stdio \ -blockdev node-name=rom,driver=file,filename=(pwd)/pc-bios/edk2-aarch64-code.fd,read-only=true \ -blockdev node-name=efivars,driver=file,filename=$HOME/images/qemu-arm64-efivars \ -m 8192 \ -object memory-backend-memfd,id=mem,size=8G,share=on \ -kernel /home/alex/lsrc/linux.git/builds/arm64/arch/arm64/boot/Image -append "root=/dev/sda2 console=ttyAMA0 systemd.unit=benchmark-stress-ng.service" \ -display none -d trace:load_atom\*_fallback,trace:store_atom\*_fallback With: -cpu neoverse-v1,pauth-impdef=on => 2203343 With: -cpu cortex-a76 => 0 Reviewed-by: Richard Henderson Reviewed-by: Pierrick Bouvier Signed-off-by: Alex Bennée Message-Id: <20241023113406.1284676-9-alex.bennee@linaro.org> --- accel/tcg/user-exec.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'accel/tcg/user-exec.c') diff --git a/accel/tcg/user-exec.c b/accel/tcg/user-exec.c index 51b2c16dbe..aa8af52cc3 100644 --- a/accel/tcg/user-exec.c +++ b/accel/tcg/user-exec.c @@ -29,7 +29,7 @@ #include "exec/page-protection.h" #include "exec/helper-proto.h" #include "qemu/atomic128.h" -#include "trace/trace-root.h" +#include "trace.h" #include "tcg/tcg-ldst.h" #include "internal-common.h" #include "internal-target.h" -- cgit 1.4.1