Skip to content

Commit

Permalink
perf/x86/intel/lbr: Use dynamic data structure for task_ctx
Browse files Browse the repository at this point in the history 
The type of task_ctx is hardcoded as struct x86_perf_task_context,
which doesn't apply for Architecture LBR. For example, Architecture LBR
doesn't have the TOS MSR. The number of LBR entries is variable. A new
struct will be introduced for Architecture LBR. Perf has to determine
the type of task_ctx at run time.

The type of task_ctx pointer is changed to 'void *', which will be
determined at run time.

The generic LBR optimization can be shared between Architecture LBR and
model-specific LBR. Both need to access the structure for the generic
LBR optimization. A helper task_context_opt() is introduced to retrieve
the pointer of the structure at run time.

Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/1593780569-62993-7-git-send-email-kan.liang@linux.intel.com
  • Loading branch information
Kan Liang authored and Peter Zijlstra committed Jul 8, 2020
1 parent 530bfff commit f42be86
Show file tree
Hide file tree
Showing 2 changed files with 32 additions and 34 deletions.
59 changes: 26 additions & 33 deletions arch/x86/events/intel/lbr.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -355,18 +355,17 @@ void intel_pmu_lbr_restore(void *ctx)
wrmsrl(MSR_LBR_SELECT, task_ctx->lbr_sel);
}

static __always_inline bool
lbr_is_reset_in_cstate(struct x86_perf_task_context *task_ctx)
static __always_inline bool lbr_is_reset_in_cstate(void *ctx)
{
return !rdlbr_from(task_ctx->tos);
return !rdlbr_from(((struct x86_perf_task_context *)ctx)->tos);
}

static void __intel_pmu_lbr_restore(struct x86_perf_task_context *task_ctx)
static void __intel_pmu_lbr_restore(void *ctx)
{
struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);

if (task_ctx->opt.lbr_callstack_users == 0 ||
task_ctx->opt.lbr_stack_state == LBR_NONE) {
if (task_context_opt(ctx)->lbr_callstack_users == 0 ||
task_context_opt(ctx)->lbr_stack_state == LBR_NONE) {
intel_pmu_lbr_reset();
return;
}
Expand All @@ -376,16 +375,16 @@ static void __intel_pmu_lbr_restore(struct x86_perf_task_context *task_ctx)
* - No one else touched them, and
* - Was not cleared in Cstate
*/
if ((task_ctx == cpuc->last_task_ctx) &&
(task_ctx->opt.log_id == cpuc->last_log_id) &&
!lbr_is_reset_in_cstate(task_ctx)) {
task_ctx->opt.lbr_stack_state = LBR_NONE;
if ((ctx == cpuc->last_task_ctx) &&
(task_context_opt(ctx)->log_id == cpuc->last_log_id) &&
!lbr_is_reset_in_cstate(ctx)) {
task_context_opt(ctx)->lbr_stack_state = LBR_NONE;
return;
}

x86_pmu.lbr_restore(task_ctx);
x86_pmu.lbr_restore(ctx);

task_ctx->opt.lbr_stack_state = LBR_NONE;
task_context_opt(ctx)->lbr_stack_state = LBR_NONE;
}

void intel_pmu_lbr_save(void *ctx)
Expand Down Expand Up @@ -415,27 +414,27 @@ void intel_pmu_lbr_save(void *ctx)
rdmsrl(MSR_LBR_SELECT, task_ctx->lbr_sel);
}

static void __intel_pmu_lbr_save(struct x86_perf_task_context *task_ctx)
static void __intel_pmu_lbr_save(void *ctx)
{
struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);

if (task_ctx->opt.lbr_callstack_users == 0) {
task_ctx->opt.lbr_stack_state = LBR_NONE;
if (task_context_opt(ctx)->lbr_callstack_users == 0) {
task_context_opt(ctx)->lbr_stack_state = LBR_NONE;
return;
}

x86_pmu.lbr_save(task_ctx);
x86_pmu.lbr_save(ctx);

task_ctx->opt.lbr_stack_state = LBR_VALID;
task_context_opt(ctx)->lbr_stack_state = LBR_VALID;

cpuc->last_task_ctx = task_ctx;
cpuc->last_log_id = ++task_ctx->opt.log_id;
cpuc->last_task_ctx = ctx;
cpuc->last_log_id = ++task_context_opt(ctx)->log_id;
}

void intel_pmu_lbr_swap_task_ctx(struct perf_event_context *prev,
struct perf_event_context *next)
{
struct x86_perf_task_context *prev_ctx_data, *next_ctx_data;
void *prev_ctx_data, *next_ctx_data;

swap(prev->task_ctx_data, next->task_ctx_data);

Expand All @@ -451,14 +450,14 @@ void intel_pmu_lbr_swap_task_ctx(struct perf_event_context *prev,
if (!prev_ctx_data || !next_ctx_data)
return;

swap(prev_ctx_data->opt.lbr_callstack_users,
next_ctx_data->opt.lbr_callstack_users);
swap(task_context_opt(prev_ctx_data)->lbr_callstack_users,
task_context_opt(next_ctx_data)->lbr_callstack_users);
}

void intel_pmu_lbr_sched_task(struct perf_event_context *ctx, bool sched_in)
{
struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
struct x86_perf_task_context *task_ctx;
void *task_ctx;

if (!cpuc->lbr_users)
return;
Expand Down Expand Up @@ -495,7 +494,6 @@ static inline bool branch_user_callstack(unsigned br_sel)
void intel_pmu_lbr_add(struct perf_event *event)
{
struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
struct x86_perf_task_context *task_ctx;

if (!x86_pmu.lbr_nr)
return;
Expand All @@ -505,10 +503,8 @@ void intel_pmu_lbr_add(struct perf_event *event)

cpuc->br_sel = event->hw.branch_reg.reg;

if (branch_user_callstack(cpuc->br_sel) && event->ctx->task_ctx_data) {
task_ctx = event->ctx->task_ctx_data;
task_ctx->opt.lbr_callstack_users++;
}
if (branch_user_callstack(cpuc->br_sel) && event->ctx->task_ctx_data)
task_context_opt(event->ctx->task_ctx_data)->lbr_callstack_users++;

/*
* Request pmu::sched_task() callback, which will fire inside the
Expand Down Expand Up @@ -539,16 +535,13 @@ void intel_pmu_lbr_add(struct perf_event *event)
void intel_pmu_lbr_del(struct perf_event *event)
{
struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
struct x86_perf_task_context *task_ctx;

if (!x86_pmu.lbr_nr)
return;

if (branch_user_callstack(cpuc->br_sel) &&
event->ctx->task_ctx_data) {
task_ctx = event->ctx->task_ctx_data;
task_ctx->opt.lbr_callstack_users--;
}
event->ctx->task_ctx_data)
task_context_opt(event->ctx->task_ctx_data)->lbr_callstack_users--;

if (event->hw.flags & PERF_X86_EVENT_LBR_SELECT)
cpuc->lbr_select = 0;
Expand Down
7 changes: 6 additions & 1 deletion arch/x86/events/perf_event.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -247,7 +247,7 @@ struct cpu_hw_events {
struct perf_branch_entry lbr_entries[MAX_LBR_ENTRIES];
struct er_account *lbr_sel;
u64 br_sel;
struct x86_perf_task_context *last_task_ctx;
void *last_task_ctx;
int last_log_id;
int lbr_select;

Expand Down Expand Up @@ -800,6 +800,11 @@ static struct perf_pmu_events_ht_attr event_attr_##v = { \
struct pmu *x86_get_pmu(void);
extern struct x86_pmu x86_pmu __read_mostly;

static __always_inline struct x86_perf_task_context_opt *task_context_opt(void *ctx)
{
return &((struct x86_perf_task_context *)ctx)->opt;
}

static inline bool x86_pmu_has_lbr_callstack(void)
{
return x86_pmu.lbr_sel_map &&
Expand Down

0 comments on commit f42be86

Please sign in to comment.