d363c2a880
When using perf timehist, sch delay is only computed for a waking task, not for a pre empted task. This patches changes sch delay to account for both. This makes sense as testing scheduling policy need to consider the effect of scheduling delay globally, not only for waking tasks. Example of `perf timehist` report before the patch for `stress` task competing with each other. First column is wait time, second column sch delay, third column runtime. 1.492060 [0000] s stress[81] 1.999 0.000 2.000 R next: stress[83] 1.494060 [0000] s stress[83] 2.000 0.000 2.000 R next: stress[81] 1.496060 [0000] s stress[81] 2.000 0.000 2.000 R next: stress[83] 1.498060 [0000] s stress[83] 2.000 0.000 1.999 R next: stress[81] After the patch, it looks like this (note that all wait time is not zero anymore): 1.492060 [0000] s stress[81] 1.999 1.999 2.000 R next: stress[83] 1.494060 [0000] s stress[83] 2.000 2.000 2.000 R next: stress[81] 1.496060 [0000] s stress[81] 2.000 2.000 2.000 R next: stress[83] 1.498060 [0000] s stress[83] 2.000 2.000 1.999 R next: stress[81] Signed-off-by: Fernand Sieber <sieberf@amazon.com> Reviewed-by: Madadi Vineeth Reddy <vineethr@linux.ibm.com> Signed-off-by: Namhyung Kim <namhyung@kernel.org> Link: https://lore.kernel.org/r/20240618090339.87482-1-sieberf@amazon.com
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.