A lot of scx_lavd's options do not clearly explain what they do. Add
some short explanations, clean up the existing ones, and direct the user
to read the in-code documentation for more info.
This option chooses little (effiency) cores over big (performance) cores
to save power consumption for core compaction.
Signed-off-by: Changwoo Min <changwoo@igalia.com>
The changes include 1) chopping down a big function into smaller ones
for readability and maintainability and 2) using the interior mutability
pattern (Cell and RefCell) to avoid unnecessary clone() calls. There
are no functional changes.
Signed-off-by: Changwoo Min <changwoo@igalia.com>
Put a performance-critical task to a performance critical queue and a
regular task to a regular queue.
Signed-off-by: Changwoo Min <changwoo@igalia.com>
- Use .enumerate() consistently while building the cpu_fids vector.
- Use .then_with() to chain .cmp() when sorting cpu_fids.
Both reduce visual clutter.
With optimizations of calculatring ineligibility duration, now the
scheduler works well under heavy load without 2-level scheduling, so we
drop it for simplicitiy.
Signed-off-by: Changwoo Min <changwoo@igalia.com>
This commit include a few changes:
- treat a new forked task more conservatively
- defer the execution of more tasks for longer time using ineligibility duration
- consider if a task is waken up in calculating ineligibility duration
L or R: Latency-critical, Regular
H or I: performance-Hungry, performance-Insensitive
B or T: Big, liTtle
E or G: Eligible, Greedy
P or N: Preemption, Not
Signed-off-by: Changwoo Min <changwoo@igalia.com>
Tuning the time slice under high load and change the kick/tick margins
for preemption more conservative. Especially, aggressive IPI-based
preemption (kick) causes performance unstability.
Signed-off-by: Changwoo Min <changwoo@igalia.com>
Instead of using coarse-grained log(), let's directly use the ratio of
task's service time. Also, the virtual dealine equation is also updated
to reflect this change.
Signed-off-by: Changwoo Min <changwoo@igalia.com>
The max_entries parameter in BPF_MAP_TYPE_PERCPU_ARRAY defines the
number of values per CPU and for cpu_ctx_stor we only need one item: the
CPU context.
Set max_entries to 1 to avoid allocating unnecessary memory and slightly
reduce the memory footprint.
Signed-off-by: Andrea Righi <righi.andrea@gmail.com>
We introduce two-level scheduling similar to scx_bpfland. The two-level
scheduling consists of two DSQs: 1) latency-critical run queue and 2)
regular run queue. The scheduler prioritizes scheduling tasks on the
latency-critical queue but makes its best effort to schedule tasks on
the regular queue. The scheduler could be more resilient under heavy
load by segregating regular, non-latency-critical tasks from
latency-critical tasks.
Signed-off-by: Changwoo Min <changwoo@igalia.com>
The max frequency information from topology (from sysfs) seems not
always true. In some installations, it returns zero for all CPUs. In
this case, let's just consider all CPUs have the same capacity (1024),
hoping the kernel can give more preceise information.
Signed-off-by: Changwoo Min <changwoo@igalia.com>
