diff options
| -rw-r--r-- | kernel/sched/ext.c | 17 | ||||
| -rw-r--r-- | tools/sched_ext/scx_qmap.bpf.c | 15 | ||||
| -rw-r--r-- | tools/sched_ext/scx_qmap.c | 8 |
3 files changed, 38 insertions, 2 deletions
diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c index 213793d086d7..89bcca84d6b5 100644 --- a/kernel/sched/ext.c +++ b/kernel/sched/ext.c @@ -8,6 +8,7 @@ enum scx_consts { SCX_DSP_DFL_MAX_BATCH = 32, + SCX_DSP_MAX_LOOPS = 32, SCX_WATCHDOG_MAX_TIMEOUT = 30 * HZ, SCX_EXIT_BT_LEN = 64, @@ -665,6 +666,7 @@ static struct kobject *scx_root_kobj; #define CREATE_TRACE_POINTS #include <trace/events/sched_ext.h> +static void scx_bpf_kick_cpu(s32 cpu, u64 flags); static __printf(3, 4) void scx_ops_exit_kind(enum scx_exit_kind kind, s64 exit_code, const char *fmt, ...); @@ -1906,6 +1908,7 @@ static int balance_scx(struct rq *rq, struct task_struct *prev, { struct scx_dsp_ctx *dspc = this_cpu_ptr(scx_dsp_ctx); bool prev_on_scx = prev->sched_class == &ext_sched_class; + int nr_loops = SCX_DSP_MAX_LOOPS; bool has_tasks = false; lockdep_assert_rq_held(rq); @@ -1962,6 +1965,20 @@ static int balance_scx(struct rq *rq, struct task_struct *prev, goto has_tasks; if (consume_dispatch_q(rq, rf, &scx_dsq_global)) goto has_tasks; + + /* + * ops.dispatch() can trap us in this loop by repeatedly + * dispatching ineligible tasks. Break out once in a while to + * allow the watchdog to run. As IRQ can't be enabled in + * balance(), we want to complete this scheduling cycle and then + * start a new one. IOW, we want to call resched_curr() on the + * next, most likely idle, task, not the current one. Use + * scx_bpf_kick_cpu() for deferred kicking. + */ + if (unlikely(!--nr_loops)) { + scx_bpf_kick_cpu(cpu_of(rq), 0); + break; + } } while (dspc->nr_tasks); goto out; diff --git a/tools/sched_ext/scx_qmap.bpf.c b/tools/sched_ext/scx_qmap.bpf.c index 5b3da28bf042..879fc9c788e5 100644 --- a/tools/sched_ext/scx_qmap.bpf.c +++ b/tools/sched_ext/scx_qmap.bpf.c @@ -31,6 +31,7 @@ char _license[] SEC("license") = "GPL"; const volatile u64 slice_ns = SCX_SLICE_DFL; const volatile u32 stall_user_nth; const volatile u32 stall_kernel_nth; +const volatile u32 dsp_inf_loop_after; const volatile u32 dsp_batch; const volatile s32 disallow_tgid; const volatile bool suppress_dump; @@ -198,6 +199,20 @@ void BPF_STRUCT_OPS(qmap_dispatch, s32 cpu, struct task_struct *prev) if (scx_bpf_consume(SHARED_DSQ)) return; + if (dsp_inf_loop_after && nr_dispatched > dsp_inf_loop_after) { + /* + * PID 2 should be kthreadd which should mostly be idle and off + * the scheduler. Let's keep dispatching it to force the kernel + * to call this function over and over again. + */ + p = bpf_task_from_pid(2); + if (p) { + scx_bpf_dispatch(p, SCX_DSQ_LOCAL, slice_ns, 0); + bpf_task_release(p); + return; + } + } + if (!(cpuc = bpf_map_lookup_elem(&cpu_ctx_stor, &zero))) { scx_bpf_error("failed to look up cpu_ctx"); return; diff --git a/tools/sched_ext/scx_qmap.c b/tools/sched_ext/scx_qmap.c index a1123a17581b..594147a710a8 100644 --- a/tools/sched_ext/scx_qmap.c +++ b/tools/sched_ext/scx_qmap.c @@ -19,13 +19,14 @@ const char help_fmt[] = "\n" "See the top-level comment in .bpf.c for more details.\n" "\n" -"Usage: %s [-s SLICE_US] [-e COUNT] [-t COUNT] [-T COUNT] [-b COUNT]\n" +"Usage: %s [-s SLICE_US] [-e COUNT] [-t COUNT] [-T COUNT] [-l COUNT] [-b COUNT]\n" " [-d PID] [-D LEN] [-p] [-v]\n" "\n" " -s SLICE_US Override slice duration\n" " -e COUNT Trigger scx_bpf_error() after COUNT enqueues\n" " -t COUNT Stall every COUNT'th user thread\n" " -T COUNT Stall every COUNT'th kernel thread\n" +" -l COUNT Trigger dispatch infinite looping after COUNT dispatches\n" " -b COUNT Dispatch upto COUNT tasks together\n" " -d PID Disallow a process from switching into SCHED_EXT (-1 for self)\n" " -D LEN Set scx_exit_info.dump buffer length\n" @@ -61,7 +62,7 @@ int main(int argc, char **argv) skel = SCX_OPS_OPEN(qmap_ops, scx_qmap); - while ((opt = getopt(argc, argv, "s:e:t:T:b:d:D:Spvh")) != -1) { + while ((opt = getopt(argc, argv, "s:e:t:T:l:b:d:D:Spvh")) != -1) { switch (opt) { case 's': skel->rodata->slice_ns = strtoull(optarg, NULL, 0) * 1000; @@ -75,6 +76,9 @@ int main(int argc, char **argv) case 'T': skel->rodata->stall_kernel_nth = strtoul(optarg, NULL, 0); break; + case 'l': + skel->rodata->dsp_inf_loop_after = strtoul(optarg, NULL, 0); + break; case 'b': skel->rodata->dsp_batch = strtoul(optarg, NULL, 0); break; |