In order to reduce the memory footprint when PVH kernel and initrd are used, we map them into memory instead of reading them. In this way we can share them between multiple instances of QEMU.
v2: - Patch 1: used g_mapped_file_new_from_fd() with 'writeble' set to 'true', since we can modify the mapped buffer. [Paolo, Peter] These are the results using a PVH kernel and initrd (cpio): - memory footprint (using smem) [MB] QEMU before now # instances USS PSS USS PSS 1 102.0M 105.8M 102.3M 106.2M 2 94.6M 101.2M 72.3M 90.1M 4 94.1M 98.0M 72.0M 81.5M 8 94.0M 96.2M 71.8M 76.9M 16 93.9M 95.1M 71.6M 74.3M Initrd size: 3.0M Kernel image size: 28M sections size [size -A -d vmlinux]: 18.9M - boot time [ms] before now qemu_init_end: 63.85 55.91 linux_start_kernel: 82.11 (+18.26) 74.51 (+18.60) linux_start_user: 169.94 (+87.83) 159.06 (+84.56) QEMU command used: ./qemu-system-x86_64 -bios /path/to/seabios/out/bios.bin -no-hpet \ -machine q35,accel=kvm,kernel_irqchip,nvdimm,sata=off,smbus=off,vmport=off \ -cpu host -m 1G -smp 1 -vga none -display none -no-user-config -nodefaults \ -kernel /path/to/vmlinux -initrd /path/to/rootfs.cpio \ -append 'root=/dev/mem0 ro console=hvc0 pci=lastbus=0 nosmap' Stefano Garzarella (2): elf-ops.h: Map into memory the ELF to load hw/i386/pc: Map into memory the initrd hw/i386/pc.c | 15 ++++++++--- include/hw/elf_ops.h | 64 ++++++++++++++++++++++++-------------------- 2 files changed, 46 insertions(+), 33 deletions(-) -- 2.20.1