Ryan Newton 5aff3b3199 sched_ext: Add a selftest for scx_bpf_dsq_peek
This commit adds two tests. The first is the most basic unit test:
make sure an empty queue peeks as empty, and when we put one element
in the queue, make sure peek returns that element.

However, even this simple test is a little complicated by the different
behavior of scx_bpf_dsq_insert in different calling contexts:
 - insert is for direct dispatch in enqueue
 - insert is delayed when called from select_cpu

In this case we split the insert and the peek that verifies the
result between enqueue/dispatch.

Note: An alternative would be to call `scx_bpf_dsq_move_to_local` on an
empty queue, which in turn calls `flush_dispatch_buf`, in order to flush
the buffered insert. Unfortunately, this is not viable within the
enqueue path, as it attempts a voluntary context switch within an RCU
read-side critical section.

The second test is a stress test that performs many peeks on all DSQs
and records the observed tasks.

Signed-off-by: Ryan Newton <newton@meta.com>
Reviewed-by: Christian Loehle <christian.loehle@arm.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
2025-10-15 06:46:36 -10:00
2022-09-28 09:02:20 +02:00
2025-02-19 14:53:27 -07:00
2025-10-12 13:42:36 -07:00
2024-03-18 03:36:32 -06:00

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.
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