linux.git/tools/testing/selftests/sched_ext, branch v6.12

sched_ext: Fix enq_last_no_enq_fails selftest

2024-10-25T22:20:29+00:00

cc9877fb7677 ("sched_ext: Improve error reporting during loading") changed
how load failures are reported so that more error context can be
communicated. This breaks the enq_last_no_enq_fails test as attach no longer
fails. The scheduler is guaranteed to be ejected on attach completion with
full error information. Update enq_last_no_enq_fails so that it checks that
the scheduler is ejected using ops.exit().

Signed-off-by: Tejun Heo 
Reported-by: Vishal Chourasia 
Link: http://lkml.kernel.org/r/Zxknp7RAVNjmdJSc@linux.ibm.com
Fixes: cc9877fb7677 ("sched_ext: Improve error reporting during loading")

scx: Fix exit selftest to use custom DSQ

2024-10-25T17:03:36+00:00

In commit 63fb3ec80516 ("sched_ext: Allow only user DSQs for
scx_bpf_consume(), scx_bpf_dsq_nr_queued() and bpf_iter_scx_dsq_new()"), we
updated the consume path to only accept user DSQs, thus making it invalid
to consume SCX_DSQ_GLOBAL. This selftest was doing that, so let's create a
custom DSQ and use that instead.  The test now passes:

[root@virtme-ng sched_ext]# ./runner -t exit
===== START =====
TEST: exit
DESCRIPTION: Verify we can cleanly exit a scheduler in multiple places
OUTPUT:
[   12.387229] sched_ext: BPF scheduler "exit" enabled
[   12.406064] sched_ext: BPF scheduler "exit" disabled (unregistered from BPF)
[   12.453325] sched_ext: BPF scheduler "exit" enabled
[   12.474064] sched_ext: BPF scheduler "exit" disabled (unregistered from BPF)
[   12.515241] sched_ext: BPF scheduler "exit" enabled
[   12.532064] sched_ext: BPF scheduler "exit" disabled (unregistered from BPF)
[   12.592063] sched_ext: BPF scheduler "exit" disabled (unregistered from BPF)
[   12.654063] sched_ext: BPF scheduler "exit" disabled (unregistered from BPF)
[   12.715062] sched_ext: BPF scheduler "exit" disabled (unregistered from BPF)
ok 1 exit #
=====  END  =====

Signed-off-by: David Vernet 
Signed-off-by: Tejun Heo

sched_ext: Fix function pointer type mismatches in BPF selftests

2024-10-24T16:56:17+00:00

Fix incompatible function pointer type warnings in sched_ext BPF selftests by
explicitly casting the function pointers when initializing struct_ops.
This addresses multiple -Wincompatible-function-pointer-types warnings from the
clang compiler where function signatures didn't match exactly.

The void * cast ensures the compiler accepts the function pointer
assignment despite minor type differences in the parameters.

Signed-off-by: Vishal Chourasia 
Signed-off-by: Tejun Heo

selftests/sched_ext: add order-only dependency of runner.o on BPFOBJ

2024-10-23T18:56:32+00:00

The runner.o may start building before libbpf headers are installed,
and as a result build fails. This happened a couple of times on
libbpf/ci test jobs:
  * https://github.com/libbpf/ci/actions/runs/11447667257/job/31849533100
  * https://github.com/theihor/libbpf-ci/actions/runs/11445162764/job/31841649552

Headers are installed in a recipe for $(BPFOBJ) target, and adding an
order-only dependency should ensure this doesn't happen.

Signed-off-by: Ihor Solodrai 
Signed-off-by: Tejun Heo

selftests: sched_ext: Add sched_ext as proper selftest target

2024-10-09T16:42:51+00:00

The sched_ext selftests is missing proper cross-compilation support, a
proper target entry, and out-of-tree build support.

When building the kselftest suite, e.g.:

  make ARCH=riscv CROSS_COMPILE=riscv64-linux-gnu-  \
    TARGETS=sched_ext SKIP_TARGETS="" O=/output/foo \
    -C tools/testing/selftests install

or:

  make ARCH=arm64 LLVM=1 TARGETS=sched_ext SKIP_TARGETS="" \
    O=/output/foo -C tools/testing/selftests install

The expectation is that the sched_ext is included, cross-built, the
correct toolchain is picked up, and placed into /output/foo.

In contrast to the BPF selftests, the sched_ext suite does not use
bpftool at test run-time, so it is sufficient to build bpftool for the
build host only.

Add ARCH, CROSS_COMPILE, OUTPUT, and TARGETS support to the sched_ext
selftest. Also, remove some variables that were unused by the
Makefile.

Signed-off-by: Björn Töpel 
Reviewed-by: Shuah Khan 
Acked-by: David Vernet 
Tested-by: Mark Brown 
Reviewed-by: Mark Brown 
Signed-off-by: Tejun Heo

sched_ext: Add cgroup support

2024-09-04T20:24:59+00:00

Add sched_ext_ops operations to init/exit cgroups, and track task migrations
and config changes. A BPF scheduler may not implement or implement only
subset of cgroup features. The implemented features can be indicated using
%SCX_OPS_HAS_CGOUP_* flags. If cgroup configuration makes use of features
that are not implemented, a warning is triggered.

While a BPF scheduler is being enabled and disabled, relevant cgroup
operations are locked out using scx_cgroup_rwsem. This avoids situations
like task prep taking place while the task is being moved across cgroups,
making things easier for BPF schedulers.

v7: - cgroup interface file visibility toggling is dropped in favor just
      warning messages. Dynamically changing interface visiblity caused more
      confusion than helping.

v6: - Updated to reflect the removal of SCX_KF_SLEEPABLE.

    - Updated to use CONFIG_GROUP_SCHED_WEIGHT and fixes for
      !CONFIG_FAIR_GROUP_SCHED && CONFIG_EXT_GROUP_SCHED.

v5: - Flipped the locking order between scx_cgroup_rwsem and
      cpus_read_lock() to avoid locking order conflict w/ cpuset. Better
      documentation around locking.

    - sched_move_task() takes an early exit if the source and destination
      are identical. This triggered the warning in scx_cgroup_can_attach()
      as it left p->scx.cgrp_moving_from uncleared. Updated the cgroup
      migration path so that ops.cgroup_prep_move() is skipped for identity
      migrations so that its invocations always match ops.cgroup_move()
      one-to-one.

v4: - Example schedulers moved into their own patches.

    - Fix build failure when !CONFIG_CGROUP_SCHED, reported by Andrea Righi.

v3: - Make scx_example_pair switch all tasks by default.

    - Convert to BPF inline iterators.

    - scx_bpf_task_cgroup() is added to determine the current cgroup from
      CPU controller's POV. This allows BPF schedulers to accurately track
      CPU cgroup membership.

    - scx_example_flatcg added. This demonstrates flattened hierarchy
      implementation of CPU cgroup control and shows significant performance
      improvement when cgroups which are nested multiple levels are under
      competition.

v2: - Build fixes for different CONFIG combinations.

Signed-off-by: Tejun Heo 
Reviewed-by: David Vernet 
Acked-by: Josh Don 
Acked-by: Hao Luo 
Acked-by: Barret Rhoden 
Reported-by: kernel test robot 
Cc: Andrea Righi

scx/selftests: Verify we can call create_dsq from prog_run

2024-07-31T17:47:34+00:00

We already have some testcases verifying that we can call
BPF_PROG_TYPE_SYSCALL progs and invoke scx_bpf_exit(). Let's extend that to
also call scx_bpf_create_dsq() so we get coverage for that as well.

Signed-off-by: David Vernet 
Signed-off-by: Tejun Heo

sched_ext: Add selftests

2024-06-18T20:09:21+00:00

Add basic selftests.

Signed-off-by: David Vernet 
Acked-by: Tejun Heo