Re: Compile kernel for various times and problem of too long time consuming

[Randy Dunlap <rdunlap@xenotime.net>]

On Sun, 7 Aug 2011 21:39:12 +0430 Amirali Shambayati wrote:

> Hi all,
> Since I want to evaluate performance improvements by changing just one
> file in kernel(noop-iosched) and compiling kernel is too much
> time-consuming, I want to know that if I compile kernel for more than
> one time, does it take similar time to first time?
> 
> I use following commands. If I don't use "make-kpkg clean" for next
> times, does it just compile the files which have been modified or it
> compile whole kernel package again?
> 
> make-kpkg clean
> fakeroot make-kpkg --initrd --append-to-version=-some-string-here
> kernel-image kernel-headers

Since I never use make-kpkg, I can only tell you that when I modified
block/noop-iosched.c and rebuilt the kernel, here is what was rebuilt:

  GEN     /lnx/src/NEXT/linux-next-20110805/X32/Makefile
  CHK     include/linux/version.h
  Using /lnx/src/NEXT/linux-next-20110805 as source for kernel
  CHK     include/generated/utsrelease.h
  CALL    /lnx/src/NEXT/linux-next-20110805/scripts/checksyscalls.sh
  CHK     include/generated/compile.h
  CHK     kernel/config_data.h
  CC      block/noop-iosched.o
  LD      block/built-in.o
  LD      vmlinux.o
  MODPOST vmlinux.o
  GEN     .version
  CHK     include/generated/compile.h
  UPD     include/generated/compile.h
  CC      init/version.o
  LD      init/built-in.o
  LD      .tmp_vmlinux1
  KSYM    .tmp_kallsyms1.S
  AS      .tmp_kallsyms1.o
  LD      .tmp_vmlinux2
  KSYM    .tmp_kallsyms2.S
  AS      .tmp_kallsyms2.o
  LD      vmlinux
  SYSMAP  System.map
  SYSMAP  .tmp_System.map
  Building modules, stage 2.
  VOFFSET arch/x86/boot/voffset.h
  CC      arch/x86/boot/version.o
  OBJCOPY arch/x86/boot/compressed/vmlinux.bin
  LZMA    arch/x86/boot/compressed/vmlinux.bin.lzma
  MODPOST 575 modules
  MKPIGGY arch/x86/boot/compressed/piggy.S
  AS      arch/x86/boot/compressed/piggy.o
  LD      arch/x86/boot/compressed/vmlinux
  ZOFFSET arch/x86/boot/zoffset.h
  OBJCOPY arch/x86/boot/vmlinux.bin
  AS      arch/x86/boot/header.o
  LD      arch/x86/boot/setup.elf
  OBJCOPY arch/x86/boot/setup.bin
  BUILD   arch/x86/boot/bzImage
Setup is 14972 bytes (padded to 15360 bytes).
System is 1287 kB
CRC 64ecf4d
Kernel: arch/x86/boot/bzImage is ready  (#18)


so it's a minimal rebuild, not a full kernel rebuild.

---
~Randy
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