Robert Yang 90e0658f2e sstate.bbclass: Only remove sstate file when task is existed
This can improve the performance a lot for "bitbake <recipe-native/cross/crosssdk>
-ccleansstate" when there are a lot of sstate files.

For example:
* Before
  $ bitbake quilt-native -ccleansstate
  - Check log.do_cleansstate:
  Removing /sstate-cache/*/*/sstate:quilt-native:x86_64-linux:0.65:r0:x86_64:3:*_package.tgz*
  Removing /sstate-cache/*/*/sstate:quilt-native:x86_64-linux:0.65:r0:x86_64:3:*_package_qa.tgz*
  Removing /sstate-cache/*/*/sstate:quilt-native:x86_64-linux:0.65:r0:x86_64:3:*_package_write_rpm.tgz*
  Removing /sstate-cache/*/*/sstate:quilt-native:x86_64-linux:0.65:r0:x86_64:3:*_packagedata.tgz*
  Removing /sstate-cache/*/sstate:quilt-native::0.65:r0::3:*_populate_lic.tgz*
  Removing /sstate-cache/*/*/sstate:quilt-native:x86_64-linux:0.65:r0:x86_64:3:*_populate_sysroot.tgz*

  There are no package tasks for quilt-native, so the first 4 lines doesn't
  make any sense, but the glob pattern "sstate-cache/*/*" is very time
  consuming when there are no disk caches. E.g., I have more than 600,000
  sstate files:
  - Without disk caches
  # echo 3 >/proc/sys/vm/drop_caches
  $ time python3 -c 'import glob; glob.glob("/sstate-cache/*/*/sstate:quilt-native:x86_64-linux:0.65:r0:x86_64:3:*_package.tgz*")'
    real    4m32.583s
    user    0m5.768s
    sys     0m12.892s

  - With disk caches (e.g., run it in the second time)
  $ time python3 -c 'import glob; glob.glob("/sstate-cache/*/*/sstate:quilt-native:x86_64-linux:0.65:r0:x86_64:3:*_package.tgz*")'
    real    0m5.128s
    user    0m2.772s
    sys     0m2.308s

  So the 4 removing *package* commands cost more than 20s or 272s in theory.

* After
  $ bitbake quilt-native -ccleansstate
  - Check log.do_cleansstate:
  Removing /sstate-cache/*/sstate:quilt-native::0.65:r0::3:*_populate_lic.tgz*
  Removing /sstate-cache/*/*/sstate:quilt-native:x86_64-linux:0.65:r0:x86_64:3:*_populate_sysroot.tgz*

  We can see that it saved 20s or 272s in theory.

(From OE-Core rev: bb2d6349ea87f090c58001f0d4348b24c2982cde)

(From OE-Core rev: aa35fbeb995b62523d44c8fad17f67d9852c594f)

Signed-off-by: Robert Yang <liezhi.yang@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
Signed-off-by: Armin Kuster <akuster808@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
2019-01-08 20:14:42 +00:00
2014-01-02 12:58:54 +00:00
2018-02-24 10:31:45 +00:00

QEMU Emulation Targets
======================

To simplify development, the build system supports building images to
work with the QEMU emulator in system emulation mode. Several architectures
are currently supported in 32 and 64 bit variants:

  * ARM (qemuarm + qemuarm64)
  * x86 (qemux86 + qemux86-64)
  * PowerPC (qemuppc only)
  * MIPS (qemumips + qemumips64)

Use of the QEMU images is covered in the Yocto Project Reference Manual.
The appropriate MACHINE variable value corresponding to the target is given
in brackets.
Description
No description provided
Readme 251 MiB