Re: [PATCH] target/riscv: Use a direct cast for better performance

On 10/7/23 02:02, Richard W.M. Jones wrote: RISCV_CPU(cs) uses a checked cast. When QOM cast debugging is enabled this adds about 5% total overhead when emulating RV64 on x86-64 host. Using a RISC-V guest with 16 vCPUs, 16 GB of guest RAM, virtio-blk disk. The guest has a copy of the qemu

Re: [PATCH] target/riscv: Use a direct cast for better performance

On 10/7/23 06:02, Richard W.M. Jones wrote: RISCV_CPU(cs) uses a checked cast. When QOM cast debugging is enabled this adds about 5% total overhead when emulating RV64 on x86-64 host. Using a RISC-V guest with 16 vCPUs, 16 GB of guest RAM, virtio-blk disk. The guest has a copy of the qemu

Re: [PATCH] target/riscv: Use a direct cast for better performance

If you're interested in how I found this problem, it was done using 'perf report -a -g' & flamegraphs. This is the flamegraph of qemu (on the host) when the guest is running the parallel compile: http://oirase.annexia.org/tmp/qemu-riscv.svg If you click into 'CPU_0/TCG' at the bottom left

[PATCH] target/riscv: Use a direct cast for better performance

RISCV_CPU(cs) uses a checked cast. When QOM cast debugging is enabled this adds about 5% total overhead when emulating RV64 on x86-64 host. Using a RISC-V guest with 16 vCPUs, 16 GB of guest RAM, virtio-blk disk. The guest has a copy of the qemu source tree. The test involves compiling the