On Mon, 26 Jun 2017, Vikas Shivappa wrote:
> DECLARE_PER_CPU(struct intel_pqr_state, pqr_state);
> DECLARE_PER_CPU_READ_MOSTLY(int, cpu_closid);
> +DECLARE_PER_CPU_READ_MOSTLY(int, cpu_rmid);
> DECLARE_STATIC_KEY_FALSE(rdt_alloc_enable_key);
> +DECLARE_STATIC_KEY_FALSE(rdt_mon_enable_key);
> +DECLARE_STATIC_KEY_FALSE(rdt_enable_key);
Please make this a two stage change. Add rdt_enable_key first and then the
monitoring stuff. Ideally you introduce rdt_enable_key here and in the
control code in one go.
> +static void __intel_rdt_sched_in(void)
> {
> - if (static_branch_likely(&rdt_alloc_enable_key)) {
> - struct intel_pqr_state *state = this_cpu_ptr(&pqr_state);
> - int closid;
> + struct intel_pqr_state *state = this_cpu_ptr(&pqr_state);
> + u32 closid = 0;
> + u32 rmid = 0;
>
> + if (static_branch_likely(&rdt_alloc_enable_key)) {
> /*
> * If this task has a closid assigned, use it.
> * Else use the closid assigned to this cpu.
> @@ -55,14 +59,31 @@ static inline void intel_rdt_sched_in(void)
> closid = current->closid;
> if (closid == 0)
> closid = this_cpu_read(cpu_closid);
> + }
> +
> + if (static_branch_likely(&rdt_mon_enable_key)) {
> + /*
> + * If this task has a rmid assigned, use it.
> + * Else use the rmid assigned to this cpu.
> + */
> + rmid = current->rmid;
> + if (rmid == 0)
> + rmid = this_cpu_read(cpu_rmid);
> + }
>
> - if (closid != state->closid) {
> - state->closid = closid;
> - wrmsr(IA32_PQR_ASSOC, state->rmid, closid);
> - }
> + if (closid != state->closid || rmid != state->rmid) {
> + state->closid = closid;
> + state->rmid = rmid;
> + wrmsr(IA32_PQR_ASSOC, rmid, closid);
This can be written smarter.
struct intel_pqr_state newstate = this_cpu_read(rdt_cpu_default);
struct intel_pqr_state *curstate = this_cpu_ptr(&pqr_state);
if (static_branch_likely(&rdt_alloc_enable_key)) {
if (current->closid)
newstate.closid = current->closid;
}
if (static_branch_likely(&rdt_mon_enable_key)) {
if (current->rmid)
newstate.rmid = current->rmid;
}
if (newstate != *curstate) {
*curstate = newstate;
wrmsr(IA32_PQR_ASSOC, newstate.rmid, newstate.closid);
}
The unconditional read of rdt_cpu_default is the right thing to do because
the default behaviour is exactly this.
Thanks,
tglx
