Commit 24247aee authored by Vikas Shivappa's avatar Vikas Shivappa Committed by Thomas Gleixner

x86/intel_rdt/cqm: Improve limbo list processing

During a mkdir, the entire limbo list is synchronously checked on each
package for free RMIDs by sending IPIs. With a large number of RMIDs (SKL
has 192) this creates a intolerable amount of work in IPIs.

Replace the IPI based checking of the limbo list with asynchronous worker
threads on each package which periodically scan the limbo list and move the
RMIDs that have:

	llc_occupancy < threshold_occupancy

on all packages to the free list.

mkdir now returns -ENOSPC if the free list and the limbo list ere empty or
returns -EBUSY if there are RMIDs on the limbo list and the free list is
empty.

Getting rid of the IPIs also simplifies the data structures and the
serialization required for handling the lists.

[ tglx: Rewrote changelog ... ]
Signed-off-by: default avatarVikas Shivappa <vikas.shivappa@linux.intel.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Cc: ravi.v.shankar@intel.com
Cc: tony.luck@intel.com
Cc: fenghua.yu@intel.com
Cc: peterz@infradead.org
Cc: eranian@google.com
Cc: vikas.shivappa@intel.com
Cc: ak@linux.intel.com
Cc: davidcc@google.com
Link: http://lkml.kernel.org/r/1502845243-20454-3-git-send-email-vikas.shivappa@linux.intel.com
parent bbc4615e
...@@ -426,6 +426,7 @@ static int domain_setup_mon_state(struct rdt_resource *r, struct rdt_domain *d) ...@@ -426,6 +426,7 @@ static int domain_setup_mon_state(struct rdt_resource *r, struct rdt_domain *d)
GFP_KERNEL); GFP_KERNEL);
if (!d->rmid_busy_llc) if (!d->rmid_busy_llc)
return -ENOMEM; return -ENOMEM;
INIT_DELAYED_WORK(&d->cqm_limbo, cqm_handle_limbo);
} }
if (is_mbm_total_enabled()) { if (is_mbm_total_enabled()) {
tsize = sizeof(*d->mbm_total); tsize = sizeof(*d->mbm_total);
...@@ -536,11 +537,33 @@ static void domain_remove_cpu(int cpu, struct rdt_resource *r) ...@@ -536,11 +537,33 @@ static void domain_remove_cpu(int cpu, struct rdt_resource *r)
list_del(&d->list); list_del(&d->list);
if (is_mbm_enabled()) if (is_mbm_enabled())
cancel_delayed_work(&d->mbm_over); cancel_delayed_work(&d->mbm_over);
if (is_llc_occupancy_enabled() && has_busy_rmid(r, d)) {
/*
* When a package is going down, forcefully
* decrement rmid->ebusy. There is no way to know
* that the L3 was flushed and hence may lead to
* incorrect counts in rare scenarios, but leaving
* the RMID as busy creates RMID leaks if the
* package never comes back.
*/
__check_limbo(d, true);
cancel_delayed_work(&d->cqm_limbo);
}
kfree(d); kfree(d);
} else if (r == &rdt_resources_all[RDT_RESOURCE_L3] && return;
cpu == d->mbm_work_cpu && is_mbm_enabled()) { }
cancel_delayed_work(&d->mbm_over);
mbm_setup_overflow_handler(d, 0); if (r == &rdt_resources_all[RDT_RESOURCE_L3]) {
if (is_mbm_enabled() && cpu == d->mbm_work_cpu) {
cancel_delayed_work(&d->mbm_over);
mbm_setup_overflow_handler(d, 0);
}
if (is_llc_occupancy_enabled() && cpu == d->cqm_work_cpu &&
has_busy_rmid(r, d)) {
cancel_delayed_work(&d->cqm_limbo);
cqm_setup_limbo_handler(d, 0);
}
} }
} }
......
...@@ -20,6 +20,8 @@ ...@@ -20,6 +20,8 @@
#define QOS_L3_MBM_TOTAL_EVENT_ID 0x02 #define QOS_L3_MBM_TOTAL_EVENT_ID 0x02
#define QOS_L3_MBM_LOCAL_EVENT_ID 0x03 #define QOS_L3_MBM_LOCAL_EVENT_ID 0x03
#define CQM_LIMBOCHECK_INTERVAL 1000
#define MBM_CNTR_WIDTH 24 #define MBM_CNTR_WIDTH 24
#define MBM_OVERFLOW_INTERVAL 1000 #define MBM_OVERFLOW_INTERVAL 1000
...@@ -187,8 +189,11 @@ struct mbm_state { ...@@ -187,8 +189,11 @@ struct mbm_state {
* @mbm_total: saved state for MBM total bandwidth * @mbm_total: saved state for MBM total bandwidth
* @mbm_local: saved state for MBM local bandwidth * @mbm_local: saved state for MBM local bandwidth
* @mbm_over: worker to periodically read MBM h/w counters * @mbm_over: worker to periodically read MBM h/w counters
* @cqm_limbo: worker to periodically read CQM h/w counters
* @mbm_work_cpu: * @mbm_work_cpu:
* worker cpu for MBM h/w counters * worker cpu for MBM h/w counters
* @cqm_work_cpu:
* worker cpu for CQM h/w counters
* @ctrl_val: array of cache or mem ctrl values (indexed by CLOSID) * @ctrl_val: array of cache or mem ctrl values (indexed by CLOSID)
* @new_ctrl: new ctrl value to be loaded * @new_ctrl: new ctrl value to be loaded
* @have_new_ctrl: did user provide new_ctrl for this domain * @have_new_ctrl: did user provide new_ctrl for this domain
...@@ -201,7 +206,9 @@ struct rdt_domain { ...@@ -201,7 +206,9 @@ struct rdt_domain {
struct mbm_state *mbm_total; struct mbm_state *mbm_total;
struct mbm_state *mbm_local; struct mbm_state *mbm_local;
struct delayed_work mbm_over; struct delayed_work mbm_over;
struct delayed_work cqm_limbo;
int mbm_work_cpu; int mbm_work_cpu;
int cqm_work_cpu;
u32 *ctrl_val; u32 *ctrl_val;
u32 new_ctrl; u32 new_ctrl;
bool have_new_ctrl; bool have_new_ctrl;
...@@ -422,7 +429,12 @@ void mkdir_mondata_subdir_allrdtgrp(struct rdt_resource *r, ...@@ -422,7 +429,12 @@ void mkdir_mondata_subdir_allrdtgrp(struct rdt_resource *r,
struct rdt_domain *d); struct rdt_domain *d);
void mon_event_read(struct rmid_read *rr, struct rdt_domain *d, void mon_event_read(struct rmid_read *rr, struct rdt_domain *d,
struct rdtgroup *rdtgrp, int evtid, int first); struct rdtgroup *rdtgrp, int evtid, int first);
void mbm_setup_overflow_handler(struct rdt_domain *dom, unsigned long delay_ms); void mbm_setup_overflow_handler(struct rdt_domain *dom,
unsigned long delay_ms);
void mbm_handle_overflow(struct work_struct *work); void mbm_handle_overflow(struct work_struct *work);
void cqm_setup_limbo_handler(struct rdt_domain *dom, unsigned long delay_ms);
void cqm_handle_limbo(struct work_struct *work);
bool has_busy_rmid(struct rdt_resource *r, struct rdt_domain *d);
void __check_limbo(struct rdt_domain *d, bool force_free);
#endif /* _ASM_X86_INTEL_RDT_H */ #endif /* _ASM_X86_INTEL_RDT_H */
...@@ -33,7 +33,7 @@ ...@@ -33,7 +33,7 @@
struct rmid_entry { struct rmid_entry {
u32 rmid; u32 rmid;
atomic_t busy; int busy;
struct list_head list; struct list_head list;
}; };
...@@ -45,13 +45,13 @@ struct rmid_entry { ...@@ -45,13 +45,13 @@ struct rmid_entry {
static LIST_HEAD(rmid_free_lru); static LIST_HEAD(rmid_free_lru);
/** /**
* @rmid_limbo_lru list of currently unused but (potentially) * @rmid_limbo_count count of currently unused but (potentially)
* dirty RMIDs. * dirty RMIDs.
* This list contains RMIDs that no one is currently using but that * This counts RMIDs that no one is currently using but that
* may have a occupancy value > intel_cqm_threshold. User can change * may have a occupancy value > intel_cqm_threshold. User can change
* the threshold occupancy value. * the threshold occupancy value.
*/ */
static LIST_HEAD(rmid_limbo_lru); unsigned int rmid_limbo_count;
/** /**
* @rmid_entry - The entry in the limbo and free lists. * @rmid_entry - The entry in the limbo and free lists.
...@@ -103,124 +103,53 @@ static u64 __rmid_read(u32 rmid, u32 eventid) ...@@ -103,124 +103,53 @@ static u64 __rmid_read(u32 rmid, u32 eventid)
return val; return val;
} }
/* static bool rmid_dirty(struct rmid_entry *entry)
* Walk the limbo list looking at any RMIDs that are flagged in the
* domain rmid_busy_llc bitmap as busy. If the reported LLC occupancy
* is below the threshold clear the busy bit and decrement the count.
* If the busy count gets to zero on an RMID we stop looking.
* This can be called from an IPI.
* We need an atomic for the busy count because multiple CPUs may check
* the same RMID at the same time.
*/
static bool __check_limbo(struct rdt_domain *d)
{
struct rmid_entry *entry;
u64 val;
list_for_each_entry(entry, &rmid_limbo_lru, list) {
if (!test_bit(entry->rmid, d->rmid_busy_llc))
continue;
val = __rmid_read(entry->rmid, QOS_L3_OCCUP_EVENT_ID);
if (val <= intel_cqm_threshold) {
clear_bit(entry->rmid, d->rmid_busy_llc);
if (atomic_dec_and_test(&entry->busy))
return true;
}
}
return false;
}
static void check_limbo(void *arg)
{ {
struct rdt_domain *d; u64 val = __rmid_read(entry->rmid, QOS_L3_OCCUP_EVENT_ID);
d = get_domain_from_cpu(smp_processor_id(),
&rdt_resources_all[RDT_RESOURCE_L3]);
if (d)
__check_limbo(d);
}
static bool has_busy_rmid(struct rdt_resource *r, struct rdt_domain *d) return val >= intel_cqm_threshold;
{
return find_first_bit(d->rmid_busy_llc, r->num_rmid) != r->num_rmid;
} }
/* /*
* Scan the limbo list and move all entries that are below the * Check the RMIDs that are marked as busy for this domain. If the
* intel_cqm_threshold to the free list. * reported LLC occupancy is below the threshold clear the busy bit and
* Return "true" if the limbo list is empty, "false" if there are * decrement the count. If the busy count gets to zero on an RMID, we
* still some RMIDs there. * free the RMID
*/ */
static bool try_freeing_limbo_rmid(void) void __check_limbo(struct rdt_domain *d, bool force_free)
{ {
struct rmid_entry *entry, *tmp; struct rmid_entry *entry;
struct rdt_resource *r; struct rdt_resource *r;
cpumask_var_t cpu_mask; u32 crmid = 1, nrmid;
struct rdt_domain *d;
bool ret = true;
int cpu;
if (list_empty(&rmid_limbo_lru))
return ret;
r = &rdt_resources_all[RDT_RESOURCE_L3]; r = &rdt_resources_all[RDT_RESOURCE_L3];
cpu = get_cpu();
/* /*
* First see if we can free up an RMID by checking busy values * Skip RMID 0 and start from RMID 1 and check all the RMIDs that
* on the local package. * are marked as busy for occupancy < threshold. If the occupancy
* is less than the threshold decrement the busy counter of the
* RMID and move it to the free list when the counter reaches 0.
*/ */
d = get_domain_from_cpu(cpu, r); for (;;) {
if (d && has_busy_rmid(r, d) && __check_limbo(d)) { nrmid = find_next_bit(d->rmid_busy_llc, r->num_rmid, crmid);
list_for_each_entry_safe(entry, tmp, &rmid_limbo_lru, list) { if (nrmid >= r->num_rmid)
if (atomic_read(&entry->busy) == 0) { break;
list_del(&entry->list);
entry = __rmid_entry(nrmid);
if (force_free || !rmid_dirty(entry)) {
clear_bit(entry->rmid, d->rmid_busy_llc);
if (!--entry->busy) {
rmid_limbo_count--;
list_add_tail(&entry->list, &rmid_free_lru); list_add_tail(&entry->list, &rmid_free_lru);
goto done;
} }
} }
crmid = nrmid + 1;
} }
}
if (!zalloc_cpumask_var(&cpu_mask, GFP_KERNEL)) { bool has_busy_rmid(struct rdt_resource *r, struct rdt_domain *d)
ret = false; {
goto done; return find_first_bit(d->rmid_busy_llc, r->num_rmid) != r->num_rmid;
}
/*
* Build a mask of other domains that have busy RMIDs
*/
list_for_each_entry(d, &r->domains, list) {
if (!cpumask_test_cpu(cpu, &d->cpu_mask) &&
has_busy_rmid(r, d))
cpumask_set_cpu(cpumask_any(&d->cpu_mask), cpu_mask);
}
if (cpumask_empty(cpu_mask)) {
ret = false;
goto free_mask;
}
/*
* Scan domains with busy RMIDs to check if they still are busy
*/
on_each_cpu_mask(cpu_mask, check_limbo, NULL, true);
/* Walk limbo list moving all free RMIDs to the &rmid_free_lru list */
list_for_each_entry_safe(entry, tmp, &rmid_limbo_lru, list) {
if (atomic_read(&entry->busy) != 0) {
ret = false;
continue;
}
list_del(&entry->list);
list_add_tail(&entry->list, &rmid_free_lru);
}
free_mask:
free_cpumask_var(cpu_mask);
done:
put_cpu();
return ret;
} }
/* /*
...@@ -231,15 +160,11 @@ static bool try_freeing_limbo_rmid(void) ...@@ -231,15 +160,11 @@ static bool try_freeing_limbo_rmid(void)
int alloc_rmid(void) int alloc_rmid(void)
{ {
struct rmid_entry *entry; struct rmid_entry *entry;
bool ret;
lockdep_assert_held(&rdtgroup_mutex); lockdep_assert_held(&rdtgroup_mutex);
if (list_empty(&rmid_free_lru)) { if (list_empty(&rmid_free_lru))
ret = try_freeing_limbo_rmid(); return rmid_limbo_count ? -EBUSY : -ENOSPC;
if (list_empty(&rmid_free_lru))
return ret ? -ENOSPC : -EBUSY;
}
entry = list_first_entry(&rmid_free_lru, entry = list_first_entry(&rmid_free_lru,
struct rmid_entry, list); struct rmid_entry, list);
...@@ -252,11 +177,12 @@ static void add_rmid_to_limbo(struct rmid_entry *entry) ...@@ -252,11 +177,12 @@ static void add_rmid_to_limbo(struct rmid_entry *entry)
{ {
struct rdt_resource *r; struct rdt_resource *r;
struct rdt_domain *d; struct rdt_domain *d;
int cpu, nbusy = 0; int cpu;
u64 val; u64 val;
r = &rdt_resources_all[RDT_RESOURCE_L3]; r = &rdt_resources_all[RDT_RESOURCE_L3];
entry->busy = 0;
cpu = get_cpu(); cpu = get_cpu();
list_for_each_entry(d, &r->domains, list) { list_for_each_entry(d, &r->domains, list) {
if (cpumask_test_cpu(cpu, &d->cpu_mask)) { if (cpumask_test_cpu(cpu, &d->cpu_mask)) {
...@@ -264,17 +190,22 @@ static void add_rmid_to_limbo(struct rmid_entry *entry) ...@@ -264,17 +190,22 @@ static void add_rmid_to_limbo(struct rmid_entry *entry)
if (val <= intel_cqm_threshold) if (val <= intel_cqm_threshold)
continue; continue;
} }
/*
* For the first limbo RMID in the domain,
* setup up the limbo worker.
*/
if (!has_busy_rmid(r, d))
cqm_setup_limbo_handler(d, CQM_LIMBOCHECK_INTERVAL);
set_bit(entry->rmid, d->rmid_busy_llc); set_bit(entry->rmid, d->rmid_busy_llc);
nbusy++; entry->busy++;
} }
put_cpu(); put_cpu();
if (nbusy) { if (entry->busy)
atomic_set(&entry->busy, nbusy); rmid_limbo_count++;
list_add_tail(&entry->list, &rmid_limbo_lru); else
} else {
list_add_tail(&entry->list, &rmid_free_lru); list_add_tail(&entry->list, &rmid_free_lru);
}
} }
void free_rmid(u32 rmid) void free_rmid(u32 rmid)
...@@ -387,6 +318,50 @@ static void mbm_update(struct rdt_domain *d, int rmid) ...@@ -387,6 +318,50 @@ static void mbm_update(struct rdt_domain *d, int rmid)
} }
} }
/*
* Handler to scan the limbo list and move the RMIDs
* to free list whose occupancy < threshold_occupancy.
*/
void cqm_handle_limbo(struct work_struct *work)
{
unsigned long delay = msecs_to_jiffies(CQM_LIMBOCHECK_INTERVAL);
int cpu = smp_processor_id();
struct rdt_resource *r;
struct rdt_domain *d;
mutex_lock(&rdtgroup_mutex);
r = &rdt_resources_all[RDT_RESOURCE_L3];
d = get_domain_from_cpu(cpu, r);
if (!d) {
pr_warn_once("Failure to get domain for limbo worker\n");
goto out_unlock;
}
__check_limbo(d, false);
if (has_busy_rmid(r, d))
schedule_delayed_work_on(cpu, &d->cqm_limbo, delay);
out_unlock:
mutex_unlock(&rdtgroup_mutex);
}
void cqm_setup_limbo_handler(struct rdt_domain *dom, unsigned long delay_ms)
{
unsigned long delay = msecs_to_jiffies(delay_ms);
struct rdt_resource *r;
int cpu;
r = &rdt_resources_all[RDT_RESOURCE_L3];
cpu = cpumask_any(&dom->cpu_mask);
dom->cqm_work_cpu = cpu;
schedule_delayed_work_on(cpu, &dom->cqm_limbo, delay);
}
void mbm_handle_overflow(struct work_struct *work) void mbm_handle_overflow(struct work_struct *work)
{ {
unsigned long delay = msecs_to_jiffies(MBM_OVERFLOW_INTERVAL); unsigned long delay = msecs_to_jiffies(MBM_OVERFLOW_INTERVAL);
...@@ -413,6 +388,7 @@ void mbm_handle_overflow(struct work_struct *work) ...@@ -413,6 +388,7 @@ void mbm_handle_overflow(struct work_struct *work)
} }
schedule_delayed_work_on(cpu, &d->mbm_over, delay); schedule_delayed_work_on(cpu, &d->mbm_over, delay);
out_unlock: out_unlock:
mutex_unlock(&rdtgroup_mutex); mutex_unlock(&rdtgroup_mutex);
} }
......
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