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SubjectRe: [PATCH RFC 01/10] perf tools: hashtable for machine threads
Em Thu, Sep 07, 2017 at 10:55:45AM -0700, kan.liang@intel.com escreveu:
> From: Kan Liang <kan.liang@intel.com>
>
> To process any events, it needs to find the thread in the machine first.
> The machine maintains a rb tree to store all threads. The rb tree is
> protected by a rw lock.
> It is not a problem for current perf which serially processing events.
> However, it will have scalability performance issue to process events in
> parallel, especially on a heave load system which have many threads.
>
> Introduce a hashtable to divide the big rb tree into many samll rb tree
> for threads. The index is thread id % hashtable size. It can reduce the
> lock contention.

<SNIP>

> +++ b/tools/perf/util/machine.h
> @@ -23,6 +23,17 @@ extern const char *ref_reloc_sym_names[];
>
> struct vdso_info;
>
> +#define MACHINE_TH_TABLE_BITS 8
> +#define MACHINE_TH_TABLE_SIZE (1 << MACHINE_TH_TABLE_BITS)
> +
> +struct machine_th {
> + struct rb_root threads;
> + pthread_rwlock_t threads_lock;
> + unsigned int nr_threads;
> + struct list_head dead_threads;
> + struct thread *last_match;
> +};
> +

Call it just "threads", no need to call it then threads->threads, but
threads->entries, also no threads->threads_lock, but threads->lock,
threads->deads, threads->nr.

MACHINE_TH_TABLE_SIZE -> THREADS__TABLE_SIZE, etc.

> struct machine {
> struct rb_node rb_node;
> pid_t pid;
> @@ -30,11 +41,7 @@ struct machine {
> bool comm_exec;
> bool kptr_restrict_warned;
> char *root_dir;
> - struct rb_root threads;
> - pthread_rwlock_t threads_lock;
> - unsigned int nr_threads;
> - struct list_head dead_threads;
> - struct thread *last_match;
> + struct machine_th threads[MACHINE_TH_TABLE_SIZE];
> struct vdso_info *vdso_info;
> struct perf_env *env;
> struct dsos dsos;
> @@ -49,6 +56,12 @@ struct machine {
> };
>
> static inline
> +struct machine_th *machine_thread(struct machine *machine, pid_t tid)

We separate the class name (machine) from the method name (thread) using
double underscores, i.e. the above becomes:

static inline threads *machine__threads(struct machine *machine, pid_t tid)

> +{
> + return &machine->threads[tid % MACHINE_TH_TABLE_SIZE];
> +}
> +
> +static inline
> struct map *__machine__kernel_map(struct machine *machine, enum map_type type)
> {
> return machine->vmlinux_maps[type];
> diff --git a/tools/perf/util/rb_resort.h b/tools/perf/util/rb_resort.h
> index 808cc45..bbd78fa 100644
> --- a/tools/perf/util/rb_resort.h
> +++ b/tools/perf/util/rb_resort.h
> @@ -143,7 +143,8 @@ struct __name##_sorted *__name = __name##_sorted__new
> __ilist->rblist.nr_entries)
>
> /* For 'struct machine->threads' */
> -#define DECLARE_RESORT_RB_MACHINE_THREADS(__name, __machine) \
> - DECLARE_RESORT_RB(__name)(&__machine->threads, __machine->nr_threads)
> +#define DECLARE_RESORT_RB_MACHINE_THREADS(__name, __machine, tid) \
> + DECLARE_RESORT_RB(__name)(&__machine->threads[tid].threads, \
> + __machine->threads[tid].nr_threads)
>
> #endif /* _PERF_RESORT_RB_H_ */
> --
> 2.5.5

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