JakeHillion/scx-upstream
1
0
Fork 0
mirror of https://github.com/sched-ext/scx.git synced 2024-11-28 13:40:28 +00:00
Code Issues Packages Projects Releases Wiki Activity

scx_lavd: reduce LAVD_CPDOM_MAX_DIST to 4

Browse Source 
The BPF verifier in the old kernel gives up to analysis the nested loop
in the consume_task(). We reduce the loop less complex by reducing
LAVD_CPDOM_MAX_DIST from 6 to 4 in order to make the verifier happy.
Note that the theoretical maximum distance is 6 (numa > llc > core type)
but there is no such hardware today, hence reducing it to 6 should be
okay in next few years, when hopefully the verifier becomes smarter.

Signed-off-by: Changwoo Min <changwoo@igalia.com>
This commit is contained in:
Changwoo Min 2024-08-23 23:07:56 +09:00
parent 950710990f
commit d1d9e97d08
3 changed files with 16 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
scheds/rust/scx_lavd/src/bpf/intf.h
View File

@ -88,8 +88,8 @@ enum consts {
LAVD_CC_CPU_PIN_INTERVAL_DIV = (LAVD_CC_CPU_PIN_INTERVAL /
LAVD_SYS_STAT_INTERVAL_NS),
LAVD_CPDOM_MAX_NR = 64, /* maximum number of compute domain (<= 64) */
LAVD_CPDOM_MAX_DIST = 6, /* maximum distance from one compute domain to another */
LAVD_CPDOM_MAX_NR = 32, /* maximum number of compute domain */
LAVD_CPDOM_MAX_DIST = 4, /* maximum distance from one compute domain to another */
LAVD_CPDOM_STARV_NS = (5ULL * NSEC_PER_MSEC),
LAVD_STATUS_STR_LEN = 5, /* {LR: Latency-critical, Regular}
@ -132,7 +132,7 @@ struct cpdom_ctx {
u8 is_active; /* if this compute domain is active */
u8 nr_neighbors[LAVD_CPDOM_MAX_DIST]; /* number of neighbors per distance */
u64 neighbor_bits[LAVD_CPDOM_MAX_DIST]; /* bitmask of neighbor bitmask per distance */
u64 cpumask[LAVD_CPU_ID_MAX/64]; /* cpumasks belongs to this compute domain */
u64 __cpumask[LAVD_CPU_ID_MAX/64]; /* cpumasks belongs to this compute domain */
};
/*

2
scheds/rust/scx_lavd/src/bpf/main.bpf.c
View File

@ -2832,7 +2832,7 @@ static s32 init_per_cpu_ctx(u64 now)
continue;
bpf_for(i, 0, LAVD_CPU_ID_MAX/64) {
u64 cpumask = cpdomc->cpumask[i];
u64 cpumask = cpdomc->__cpumask[i];
bpf_for(j, 0, 64) {
if (cpumask & 0x1LLU << j) {
cpu = (i * 64) + j;

15
scheds/rust/scx_lavd/src/main.rs
View File

@ -473,12 +473,21 @@ impl<'a> Scheduler<'a> {
for cpu_id in v.cpu_ids.iter() {
let i = cpu_id / 64;
let j = cpu_id % 64;
skel.maps.bss_data.cpdom_ctxs[v.cpdom_id].cpumask[i] |= 0x01 << j;
skel.maps.bss_data.cpdom_ctxs[v.cpdom_id].__cpumask[i] |= 0x01 << j;
}
const LAVD_CPDOM_MAX_NR: u8 = 32;
const LAVD_CPDOM_MAX_DIST: usize = 4;
if v.neighbor_map.borrow().iter().len() > LAVD_CPDOM_MAX_DIST {
panic!("The processor topology is too complex to handle in BPF.");
}
for (k, (_d, neighbors)) in v.neighbor_map.borrow().iter().enumerate() {
skel.maps.bss_data.cpdom_ctxs[v.cpdom_id].nr_neighbors[k] =
neighbors.borrow().len() as u8;
let nr_neighbors = neighbors.borrow().len() as u8;
if nr_neighbors > LAVD_CPDOM_MAX_NR {
panic!("The processor topology is too complex to handle in BPF.");
}
skel.maps.bss_data.cpdom_ctxs[v.cpdom_id].nr_neighbors[k] = nr_neighbors;
for n in neighbors.borrow().iter() {
skel.maps.bss_data.cpdom_ctxs[v.cpdom_id].neighbor_bits[k] = 0x1 << n;
}