[lttng-dev] [PATCH 1/2] lttng_ust_init_thread: initialise cached context values
Mathieu Desnoyers
mathieu.desnoyers at efficios.com
Tue Jul 19 15:39:33 EDT 2022
----- On Jul 18, 2022, at 5:59 PM, Norbert Lange via lttng-dev lttng-dev at lists.lttng.org wrote:
> Modify all relevant *_alloc_tls functions so that they take an
> argument for 'init'. Setting this to 'true' will read
> the actual context value and store it into a thread local
> cache.
>
> The function 'lttng_ust_init_thread' will use this to
> precalculate context values. Tracepoints can then avoid
> systemcalls.
Rather than integrating two unrelated things within "alloc_tls"
functions, I would prefer that we split things like this, e.g.:
keep lttng_cgroup_ns_alloc_tls() as is.
Introduce lttng_ust_cgroup_init_thread() which would
call (void)get_cgroup_ns().
Likewise for all other contexts.
Thoughts ?
Thanks,
Mathieu
>
> Signed-off-by: Norbert Lange <nolange79 at gmail.com>
> ---
> * see
> https://lore.kernel.org/all/CADYdroN3=pAe66crtsVT9aHE4T+bT61-tvHFKCuwZYkHhuyFjw@mail.gmail.com/
> * Will update docs after review, and do some more tests
> during the week
> ---
> src/lib/lttng-ust/lttng-context-cgroup-ns.c | 4 +++-
> src/lib/lttng-ust/lttng-context-ipc-ns.c | 4 +++-
> src/lib/lttng-ust/lttng-context-net-ns.c | 4 +++-
> src/lib/lttng-ust/lttng-context-procname.c | 4 +++-
> src/lib/lttng-ust/lttng-context-provider.c | 4 ++--
> src/lib/lttng-ust/lttng-context-time-ns.c | 4 +++-
> src/lib/lttng-ust/lttng-context-uts-ns.c | 4 +++-
> src/lib/lttng-ust/lttng-context-vtid.c | 4 +++-
> src/lib/lttng-ust/lttng-probes.c | 4 ++--
> src/lib/lttng-ust/lttng-tracer-core.h | 16 +++++++-------
> src/lib/lttng-ust/lttng-ust-comm.c | 24 ++++++++++-----------
> src/lib/lttng-ust/lttng-ust-statedump.c | 2 +-
> 12 files changed, 46 insertions(+), 32 deletions(-)
>
> diff --git a/src/lib/lttng-ust/lttng-context-cgroup-ns.c
> b/src/lib/lttng-ust/lttng-context-cgroup-ns.c
> index 34523ea1..3eb5ab5b 100644
> --- a/src/lib/lttng-ust/lttng-context-cgroup-ns.c
> +++ b/src/lib/lttng-ust/lttng-context-cgroup-ns.c
> @@ -155,7 +155,9 @@ error_find_context:
> /*
> * Force a read (imply TLS allocation for dlopen) of TLS variables.
> */
> -void lttng_cgroup_ns_alloc_tls(void)
> +void lttng_cgroup_ns_alloc_tls(bool init)
> {
> asm volatile ("" : : "m" (URCU_TLS(cached_cgroup_ns)));
> + if (init)
> + (void)get_cgroup_ns();
> }
> diff --git a/src/lib/lttng-ust/lttng-context-ipc-ns.c
> b/src/lib/lttng-ust/lttng-context-ipc-ns.c
> index 63401e8d..b68b939f 100644
> --- a/src/lib/lttng-ust/lttng-context-ipc-ns.c
> +++ b/src/lib/lttng-ust/lttng-context-ipc-ns.c
> @@ -153,7 +153,9 @@ error_find_context:
> /*
> * Force a read (imply TLS allocation for dlopen) of TLS variables.
> */
> -void lttng_ipc_ns_alloc_tls(void)
> +void lttng_ipc_ns_alloc_tls(bool init)
> {
> asm volatile ("" : : "m" (URCU_TLS(cached_ipc_ns)));
> + if (init)
> + (void)get_ipc_ns();
> }
> diff --git a/src/lib/lttng-ust/lttng-context-net-ns.c
> b/src/lib/lttng-ust/lttng-context-net-ns.c
> index 960591c2..93e574ad 100644
> --- a/src/lib/lttng-ust/lttng-context-net-ns.c
> +++ b/src/lib/lttng-ust/lttng-context-net-ns.c
> @@ -153,7 +153,9 @@ error_find_context:
> /*
> * Force a read (imply TLS allocation for dlopen) of TLS variables.
> */
> -void lttng_net_ns_alloc_tls(void)
> +void lttng_net_ns_alloc_tls(bool init)
> {
> asm volatile ("" : : "m" (URCU_TLS(cached_net_ns)));
> + if (init)
> + (void)get_net_ns();
> }
> diff --git a/src/lib/lttng-ust/lttng-context-procname.c
> b/src/lib/lttng-ust/lttng-context-procname.c
> index b5bf77be..95f6fe42 100644
> --- a/src/lib/lttng-ust/lttng-context-procname.c
> +++ b/src/lib/lttng-ust/lttng-context-procname.c
> @@ -122,7 +122,9 @@ error_find_context:
> /*
> * Force a read (imply TLS allocation for dlopen) of TLS variables.
> */
> -void lttng_procname_alloc_tls(void)
> +void lttng_procname_alloc_tls(bool init)
> {
> asm volatile ("" : : "m" (URCU_TLS(cached_procname)[0]));
> + if (init)
> + (void)wrapper_getprocname();
> }
> diff --git a/src/lib/lttng-ust/lttng-context-provider.c
> b/src/lib/lttng-ust/lttng-context-provider.c
> index 4e7e429f..ba24aad7 100644
> --- a/src/lib/lttng-ust/lttng-context-provider.c
> +++ b/src/lib/lttng-ust/lttng-context-provider.c
> @@ -67,7 +67,7 @@ struct lttng_ust_registered_context_provider
> *lttng_ust_context_provider_registe
> size_t name_len = strlen(provider->name);
> uint32_t hash;
>
> - lttng_ust_alloc_tls();
> + lttng_ust_alloc_tls(false);
>
> /* Provider name starts with "$app.". */
> if (strncmp("$app.", provider->name, strlen("$app.")) != 0)
> @@ -101,7 +101,7 @@ end:
>
> void lttng_ust_context_provider_unregister(struct
> lttng_ust_registered_context_provider *reg_provider)
> {
> - lttng_ust_alloc_tls();
> + lttng_ust_alloc_tls(false);
>
> if (ust_lock())
> goto end;
> diff --git a/src/lib/lttng-ust/lttng-context-time-ns.c
> b/src/lib/lttng-ust/lttng-context-time-ns.c
> index ec32a1de..a957409b 100644
> --- a/src/lib/lttng-ust/lttng-context-time-ns.c
> +++ b/src/lib/lttng-ust/lttng-context-time-ns.c
> @@ -152,7 +152,9 @@ error_find_context:
> /*
> * Force a read (imply TLS allocation for dlopen) of TLS variables.
> */
> -void lttng_time_ns_alloc_tls(void)
> +void lttng_time_ns_alloc_tls(bool init)
> {
> asm volatile ("" : : "m" (URCU_TLS(cached_time_ns)));
> + if (init)
> + (void)get_time_ns();
> }
> diff --git a/src/lib/lttng-ust/lttng-context-uts-ns.c
> b/src/lib/lttng-ust/lttng-context-uts-ns.c
> index 06a978fd..0c802188 100644
> --- a/src/lib/lttng-ust/lttng-context-uts-ns.c
> +++ b/src/lib/lttng-ust/lttng-context-uts-ns.c
> @@ -154,7 +154,9 @@ error_find_context:
> /*
> * Force a read (imply TLS allocation for dlopen) of TLS variables.
> */
> -void lttng_uts_ns_alloc_tls(void)
> +void lttng_uts_ns_alloc_tls(bool init)
> {
> asm volatile ("" : : "m" (URCU_TLS(cached_uts_ns)));
> + if (init)
> + (void)get_uts_ns();
> }
> diff --git a/src/lib/lttng-ust/lttng-context-vtid.c
> b/src/lib/lttng-ust/lttng-context-vtid.c
> index 880e34b9..d3c9863e 100644
> --- a/src/lib/lttng-ust/lttng-context-vtid.c
> +++ b/src/lib/lttng-ust/lttng-context-vtid.c
> @@ -112,7 +112,9 @@ error_find_context:
> /*
> * Force a read (imply TLS allocation for dlopen) of TLS variables.
> */
> -void lttng_vtid_alloc_tls(void)
> +void lttng_vtid_alloc_tls(bool init)
> {
> asm volatile ("" : : "m" (URCU_TLS(cached_vtid)));
> + if (init)
> + (void)wrapper_getvtid();
> }
> diff --git a/src/lib/lttng-ust/lttng-probes.c b/src/lib/lttng-ust/lttng-probes.c
> index e8e08ff1..314cb7a0 100644
> --- a/src/lib/lttng-ust/lttng-probes.c
> +++ b/src/lib/lttng-ust/lttng-probes.c
> @@ -231,7 +231,7 @@ struct lttng_ust_registered_probe
> *lttng_ust_probe_register(const struct lttng_u
> {
> struct lttng_ust_registered_probe *reg_probe = NULL;
>
> - lttng_ust_alloc_tls();
> + lttng_ust_alloc_tls(false);
>
> /*
> * If version mismatch, don't register, but don't trigger assert
> @@ -269,7 +269,7 @@ end:
>
> void lttng_ust_probe_unregister(struct lttng_ust_registered_probe *reg_probe)
> {
> - lttng_ust_alloc_tls();
> + lttng_ust_alloc_tls(false);
>
> if (!reg_probe)
> return;
> diff --git a/src/lib/lttng-ust/lttng-tracer-core.h
> b/src/lib/lttng-ust/lttng-tracer-core.h
> index eadc43ed..dbb3bd9f 100644
> --- a/src/lib/lttng-ust/lttng-tracer-core.h
> +++ b/src/lib/lttng-ust/lttng-tracer-core.h
> @@ -34,28 +34,28 @@ void ust_lock_nocheck(void)
> void ust_unlock(void)
> __attribute__((visibility("hidden")));
>
> -void lttng_ust_alloc_tls(void)
> +void lttng_ust_alloc_tls(bool init)
> __attribute__((visibility("hidden")));
>
> -void lttng_vtid_alloc_tls(void)
> +void lttng_vtid_alloc_tls(bool init)
> __attribute__((visibility("hidden")));
>
> -void lttng_procname_alloc_tls(void)
> +void lttng_procname_alloc_tls(bool init)
> __attribute__((visibility("hidden")));
>
> -void lttng_cgroup_ns_alloc_tls(void)
> +void lttng_cgroup_ns_alloc_tls(bool init)
> __attribute__((visibility("hidden")));
>
> -void lttng_ipc_ns_alloc_tls(void)
> +void lttng_ipc_ns_alloc_tls(bool init)
> __attribute__((visibility("hidden")));
>
> -void lttng_net_ns_alloc_tls(void)
> +void lttng_net_ns_alloc_tls(bool init)
> __attribute__((visibility("hidden")));
>
> -void lttng_time_ns_alloc_tls(void)
> +void lttng_time_ns_alloc_tls(bool init)
> __attribute__((visibility("hidden")));
>
> -void lttng_uts_ns_alloc_tls(void)
> +void lttng_uts_ns_alloc_tls(bool init)
> __attribute__((visibility("hidden")));
>
> const char *lttng_ust_obj_get_name(int id)
> diff --git a/src/lib/lttng-ust/lttng-ust-comm.c
> b/src/lib/lttng-ust/lttng-ust-comm.c
> index 7f34efe7..ba0bd985 100644
> --- a/src/lib/lttng-ust/lttng-ust-comm.c
> +++ b/src/lib/lttng-ust/lttng-ust-comm.c
> @@ -407,21 +407,21 @@ void lttng_lttng_ust_urcu_alloc_tls(void)
> (void) lttng_ust_urcu_read_ongoing();
> }
>
> -void lttng_ust_alloc_tls(void)
> +void lttng_ust_alloc_tls(bool init)
> {
> lttng_lttng_ust_urcu_alloc_tls();
> lttng_ringbuffer_alloc_tls();
> - lttng_vtid_alloc_tls();
> + lttng_vtid_alloc_tls(init);
> lttng_nest_count_alloc_tls();
> - lttng_procname_alloc_tls();
> + lttng_procname_alloc_tls(init);
> lttng_ust_mutex_nest_alloc_tls();
> lttng_ust_perf_counter_alloc_tls();
> lttng_ust_common_alloc_tls();
> - lttng_cgroup_ns_alloc_tls();
> - lttng_ipc_ns_alloc_tls();
> - lttng_net_ns_alloc_tls();
> - lttng_time_ns_alloc_tls();
> - lttng_uts_ns_alloc_tls();
> + lttng_cgroup_ns_alloc_tls(init);
> + lttng_ipc_ns_alloc_tls(init);
> + lttng_net_ns_alloc_tls(init);
> + lttng_time_ns_alloc_tls(init);
> + lttng_uts_ns_alloc_tls(init);
> lttng_ust_ring_buffer_client_discard_alloc_tls();
> lttng_ust_ring_buffer_client_discard_rt_alloc_tls();
> lttng_ust_ring_buffer_client_overwrite_alloc_tls();
> @@ -446,7 +446,7 @@ void lttng_ust_init_thread(void)
> * ensure those are initialized before a signal handler nesting over
> * this thread attempts to use them.
> */
> - lttng_ust_alloc_tls();
> + lttng_ust_alloc_tls(true);
> }
>
> int lttng_get_notify_socket(void *owner)
> @@ -1815,7 +1815,7 @@ void *ust_listener_thread(void *arg)
> int sock, ret, prev_connect_failed = 0, has_waited = 0, fd;
> long timeout;
>
> - lttng_ust_alloc_tls();
> + lttng_ust_alloc_tls(false);
> /*
> * If available, add '-ust' to the end of this thread's
> * process name
> @@ -2183,7 +2183,7 @@ void lttng_ust_ctor(void)
> * to be the dynamic linker mutex) and ust_lock, taken within
> * the ust lock.
> */
> - lttng_ust_alloc_tls();
> + lttng_ust_alloc_tls(false);
>
> lttng_ust_loaded = 1;
>
> @@ -2497,7 +2497,7 @@ void lttng_ust_before_fork(sigset_t *save_sigset)
> int ret;
>
> /* Allocate lttng-ust TLS. */
> - lttng_ust_alloc_tls();
> + lttng_ust_alloc_tls(false);
>
> if (URCU_TLS(lttng_ust_nest_count))
> return;
> diff --git a/src/lib/lttng-ust/lttng-ust-statedump.c
> b/src/lib/lttng-ust/lttng-ust-statedump.c
> index 309a98fa..ee180a0d 100644
> --- a/src/lib/lttng-ust/lttng-ust-statedump.c
> +++ b/src/lib/lttng-ust/lttng-ust-statedump.c
> @@ -557,7 +557,7 @@ void lttng_ust_dl_update(void *ip)
> * Force the allocation of lttng-ust TLS variables when called from
> * dlopen/dlclose instrumentation.
> */
> - lttng_ust_alloc_tls();
> + lttng_ust_alloc_tls(false);
>
> data.exec_found = 0;
> data.first = true;
> --
> 2.35.1
>
> _______________________________________________
> lttng-dev mailing list
> lttng-dev at lists.lttng.org
> https://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev
--
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com
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