From: Fenghua Yu <[email protected]> When "cpus" is changed in a rdtgroup, the current code doesn't update PQR_ASSOC registers with new closid in the cpus write operation. The PQR_ASSOC registers are updated asynchronously later when new processes are scheduled in on the CPUs.
A process may run on a CPU for long time without being switched to another process, e.g. high performance computing or real time cases. Then closid in the PQR_ASSOC register on the CPU is not updated for long time until a new process is switched in. This patch updates closid in PQR_ASSOC synchronously when writing cpus to avoid the above issue. Signed-off-by: Fenghua Yu <[email protected]> --- arch/x86/kernel/cpu/intel_rdt_rdtgroup.c | 53 ++++++++++++++++++++------------ 1 file changed, 34 insertions(+), 19 deletions(-) diff --git a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c index 416b95e..a45f2ba 100644 --- a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c +++ b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c @@ -191,6 +191,31 @@ static int rdtgroup_cpus_show(struct kernfs_open_file *of, return ret; } +/* + * MSR_IA32_PQR_ASSOC is scoped per logical CPU, so all updates + * are always in thread context. + */ +static void rdt_update_pqr_assoc_closid(void *v) +{ + struct intel_pqr_state *state = this_cpu_ptr(&pqr_state); + + state->closid = *(int *)v; + wrmsr(MSR_IA32_PQR_ASSOC, state->rmid, state->closid); +} + +static void rdt_update_pqr_assoc(const struct cpumask *cpu_mask, int closid) +{ + int cpu = get_cpu(); + + /* Update PQR_ASSOC MSR on this cpu if it's in cpu_mask. */ + if (cpumask_test_cpu(cpu, cpu_mask)) + rdt_update_pqr_assoc_closid(&closid); + /* Update PQR_ASSOC MSR on the rest of cpus. */ + smp_call_function_many(cpu_mask, rdt_update_pqr_assoc_closid, + &closid, 1); + put_cpu(); +} + static ssize_t rdtgroup_cpus_write(struct kernfs_open_file *of, char *buf, size_t nbytes, loff_t off) { @@ -238,6 +263,9 @@ static ssize_t rdtgroup_cpus_write(struct kernfs_open_file *of, &rdtgroup_default.cpu_mask, tmpmask); for_each_cpu(cpu, tmpmask) per_cpu(cpu_closid, cpu) = 0; + + /* Update PQR_ASSOC registers on the dropped cpus */ + rdt_update_pqr_assoc(tmpmask, rdtgroup_default.closid); } /* @@ -253,6 +281,9 @@ static ssize_t rdtgroup_cpus_write(struct kernfs_open_file *of, } for_each_cpu(cpu, tmpmask) per_cpu(cpu_closid, cpu) = rdtgrp->closid; + + /* Update PQR_ASSOC registers on the added cpus */ + rdt_update_pqr_assoc(tmpmask, rdtgrp->closid); } /* Done pushing/pulling - update this group with new mask */ @@ -783,18 +814,6 @@ static int reset_all_cbms(struct rdt_resource *r) } /* - * MSR_IA32_PQR_ASSOC is scoped per logical CPU, so all updates - * are always in thread context. - */ -static void rdt_reset_pqr_assoc_closid(void *v) -{ - struct intel_pqr_state *state = this_cpu_ptr(&pqr_state); - - state->closid = 0; - wrmsr(MSR_IA32_PQR_ASSOC, state->rmid, 0); -} - -/* * Forcibly remove all of subdirectories under root. */ static void rmdir_all_sub(void) @@ -809,13 +828,9 @@ static void rmdir_all_sub(void) t->closid = 0; read_unlock(&tasklist_lock); - get_cpu(); - /* Reset PQR_ASSOC MSR on this cpu. */ - rdt_reset_pqr_assoc_closid(NULL); - /* Reset PQR_ASSOC MSR on the rest of cpus. */ - smp_call_function_many(cpu_online_mask, rdt_reset_pqr_assoc_closid, - NULL, 1); - put_cpu(); + /* Reset PQR_ASSOC MSR on all online cpus */ + rdt_update_pqr_assoc(cpu_online_mask, 0); + list_for_each_entry_safe(rdtgrp, tmp, &rdt_all_groups, rdtgroup_list) { /* Remove each rdtgroup other than root */ if (rdtgrp == &rdtgroup_default) -- 2.5.0
