Re: [Qemu-devel] [PATCH] qemu:cpuid: speedup test by 3x times if grub2 is available

[Eduardo Habkost]

On Wed, Feb 13, 2013 at 05:17:44PM +0100, Igor Mammedov wrote:
> qemu boots from disk image 3 times faster than direct kernel load.

That's surprising. Do you have any idea why that happens?

(CCing qemu-devel in case other QEMU developers can explain it)


> Use grub2-mkrescue tool to create boot image with test kernel if available
> and do image boot then.
> On FC17 it reduces 1 VM run from ~15 sec to ~5sec.
> 
> Signed-off-by: Igor Mammedov <address@hidden>
> ---
>  qemu/tests/cpuid.py                    |   11 +++++++++--
>  shared/deps/cpuid_test_kernel/Makefile |   18 ++++++++++++++++--
>  shared/deps/cpuid_test_kernel/grub.cfg |    8 ++++++++
>  3 files changed, 33 insertions(+), 4 deletions(-)
>  create mode 100644 shared/deps/cpuid_test_kernel/grub.cfg
> 
> diff --git a/qemu/tests/cpuid.py b/qemu/tests/cpuid.py
> index 5065c6a..731411c 100644
> --- a/qemu/tests/cpuid.py
> +++ b/qemu/tests/cpuid.py
> @@ -118,13 +118,20 @@ def run_cpuid(test, params, env):
>                                         "cpuid_test_kernel")
>          os.chdir(test_kernel_dir)
>          utils.make("cpuid_dump_kernel.bin")
> +        utils.make("boot.img", ignore_status=True)
> +        cmdres = utils.run("cd %s && ls boot.img" % test_kernel_dir, 
> ignore_status=True)

Why fork a shell just to check if a file exists? You can simply use
"os.path.exists('%s/boot.img' % (test_kernel_dir))" or
"os.path.exists(os.path.join(test_kernel_dir, 'boot.img'))".

The rest of the patch looks good to me.

I wonder if we could make this a generic "boot kernel image" function,
that uses grub2-mkrescue if available, and -kernel otherwise. I believe
other test cases may benefit for a general mechanism to boot test
kernels.

>  
>          vm_name = params.get('main_vm')
>          params_b = params.copy()
> -        params_b["kernel"] = os.path.join(test_kernel_dir, 
> "cpuid_dump_kernel.bin")
> +        if cmdres.exit_status == 0:
> +            params_b["image_name_custom"] = os.path.join(test_kernel_dir, 
> "boot.img")
> +            params_b["image_format_custom"] = ""
> +            params_b["images"] = "custom"
> +        else:
> +            params_b["kernel"] = os.path.join(test_kernel_dir, 
> "cpuid_dump_kernel.bin")
> +            del params_b["images"]
>          params_b["cpu_model"] = cpu_model
>          params_b["cpu_model_flags"] = feature
> -        del params_b["images"]
>          del params_b["nics"]
>          env_process.preprocess_vm(self, params_b, env, vm_name)
>          vm = env.get_vm(vm_name)
> diff --git a/shared/deps/cpuid_test_kernel/Makefile 
> b/shared/deps/cpuid_test_kernel/Makefile
> index 0e34c43..5999804 100644
> --- a/shared/deps/cpuid_test_kernel/Makefile
> +++ b/shared/deps/cpuid_test_kernel/Makefile
> @@ -1,10 +1,24 @@
>  CFLAGS  := -m32 -fno-stack-protector -fno-builtin -nostdinc -O -g -Wall -I.
>  LDFLAGS := -nostdlib -Wl,-N -Wl,-Ttext -Wl,100000
>  
> -all: cpuid_dump_kernel.bin
> +boot := $(shell sh -c 'which grub2-mkrescue 2>/dev/null && echo 
> grub2boot.img')
> +
> +all: cpuid_dump_kernel.bin boot.img
>  
>  cpuid_dump_kernel.bin: boot.S main.c test.c
>       $(CC) -o $@ $(CFLAGS) $^ $(LDFLAGS)
> +     ln -s $@ kernel.bin
> +
> +boot.img: $(boot)
> +
> +
> +grub2boot.img:
> +     mkdir -p iso/boot/grub
> +     cp -f grub.cfg iso/boot/grub
> +     cp -f kernel.bin iso/
> +     grub2-mkrescue -o boot.img iso
>  
>  clean:
> -     rm -f *.o *.bin
> +     rm -rf *.o *.bin iso *.img
> +
> +.PHONY: grub2boot.img
> diff --git a/shared/deps/cpuid_test_kernel/grub.cfg 
> b/shared/deps/cpuid_test_kernel/grub.cfg
> new file mode 100644
> index 0000000..aeb5b2b
> --- /dev/null
> +++ b/shared/deps/cpuid_test_kernel/grub.cfg
> @@ -0,0 +1,8 @@
> +set timeout=0
> +set default=0
> +
> +menuentry "test" {
> +   set root=(hd0)
> +   multiboot /kernel.bin
> +   boot
> +}
> -- 
> 1.7.1
> 

-- 
Eduardo