From 462d9189374f582166ff77b8c301b89947d016cc Mon Sep 17 00:00:00 2001 From: Andriy Berestovskyy Date: Tue, 23 Jan 2018 16:43:16 +0100 Subject: [PATCH] keepalive: fix state alignment The __rte_cache_aligned was applied to the whole array, not the array elements. This leads to a false sharing between the monitored cores. Fixes: e70a61ad50ab ("keepalive: export states") Cc: stable@dpdk.org Signed-off-by: Andriy Berestovskyy Acked-by: Remy Horton --- doc/guides/sample_app_ug/keep_alive.rst | 2 +- lib/librte_eal/common/rte_keepalive.c | 28 ++++++++++++++++--------- 2 files changed, 19 insertions(+), 11 deletions(-) diff --git a/doc/guides/sample_app_ug/keep_alive.rst b/doc/guides/sample_app_ug/keep_alive.rst index 38856d2c6e..27ed2a8b94 100644 --- a/doc/guides/sample_app_ug/keep_alive.rst +++ b/doc/guides/sample_app_ug/keep_alive.rst @@ -168,5 +168,5 @@ The rte_keepalive_mark_alive function simply sets the core state to alive. static inline void rte_keepalive_mark_alive(struct rte_keepalive *keepcfg) { - keepcfg->state_flags[rte_lcore_id()] = ALIVE; + keepcfg->live_data[rte_lcore_id()].core_state = RTE_KA_STATE_ALIVE; } diff --git a/lib/librte_eal/common/rte_keepalive.c b/lib/librte_eal/common/rte_keepalive.c index 7ddf2014d5..e0494b2010 100644 --- a/lib/librte_eal/common/rte_keepalive.c +++ b/lib/librte_eal/common/rte_keepalive.c @@ -13,8 +13,12 @@ struct rte_keepalive { /** Core Liveness. */ - enum rte_keepalive_state __rte_cache_aligned state_flags[ - RTE_KEEPALIVE_MAXCORES]; + struct { + /* + * Each element must be cache aligned to prevent false sharing. + */ + enum rte_keepalive_state core_state __rte_cache_aligned; + } live_data[RTE_KEEPALIVE_MAXCORES]; /** Last-seen-alive timestamps */ uint64_t last_alive[RTE_KEEPALIVE_MAXCORES]; @@ -67,19 +71,22 @@ rte_keepalive_dispatch_pings(__rte_unused void *ptr_timer, if (keepcfg->active_cores[idx_core] == 0) continue; - switch (keepcfg->state_flags[idx_core]) { + switch (keepcfg->live_data[idx_core].core_state) { case RTE_KA_STATE_UNUSED: break; case RTE_KA_STATE_ALIVE: /* Alive */ - keepcfg->state_flags[idx_core] = RTE_KA_STATE_MISSING; + keepcfg->live_data[idx_core].core_state = + RTE_KA_STATE_MISSING; keepcfg->last_alive[idx_core] = rte_rdtsc(); break; case RTE_KA_STATE_MISSING: /* MIA */ print_trace("Core MIA. ", keepcfg, idx_core); - keepcfg->state_flags[idx_core] = RTE_KA_STATE_DEAD; + keepcfg->live_data[idx_core].core_state = + RTE_KA_STATE_DEAD; break; case RTE_KA_STATE_DEAD: /* Dead */ - keepcfg->state_flags[idx_core] = RTE_KA_STATE_GONE; + keepcfg->live_data[idx_core].core_state = + RTE_KA_STATE_GONE; print_trace("Core died. ", keepcfg, idx_core); if (keepcfg->callback) keepcfg->callback( @@ -90,7 +97,8 @@ rte_keepalive_dispatch_pings(__rte_unused void *ptr_timer, case RTE_KA_STATE_GONE: /* Buried */ break; case RTE_KA_STATE_DOZING: /* Core going idle */ - keepcfg->state_flags[idx_core] = RTE_KA_STATE_SLEEP; + keepcfg->live_data[idx_core].core_state = + RTE_KA_STATE_SLEEP; keepcfg->last_alive[idx_core] = rte_rdtsc(); break; case RTE_KA_STATE_SLEEP: /* Idled core */ @@ -100,7 +108,7 @@ rte_keepalive_dispatch_pings(__rte_unused void *ptr_timer, keepcfg->relay_callback( keepcfg->relay_callback_data, idx_core, - keepcfg->state_flags[idx_core], + keepcfg->live_data[idx_core].core_state, keepcfg->last_alive[idx_core] ); } @@ -144,11 +152,11 @@ rte_keepalive_register_core(struct rte_keepalive *keepcfg, const int id_core) void rte_keepalive_mark_alive(struct rte_keepalive *keepcfg) { - keepcfg->state_flags[rte_lcore_id()] = RTE_KA_STATE_ALIVE; + keepcfg->live_data[rte_lcore_id()].core_state = RTE_KA_STATE_ALIVE; } void rte_keepalive_mark_sleep(struct rte_keepalive *keepcfg) { - keepcfg->state_flags[rte_lcore_id()] = RTE_KA_STATE_DOZING; + keepcfg->live_data[rte_lcore_id()].core_state = RTE_KA_STATE_DOZING; } -- 2.20.1