From 72d1e611082eda18689106a0c192f2827072713c Mon Sep 17 00:00:00 2001 From: Jiebin Sun Date: Wed, 14 Sep 2022 03:25:38 +0800 Subject: ipc/msg: mitigate the lock contention with percpu counter The msg_bytes and msg_hdrs atomic counters are frequently updated when IPC msg queue is in heavy use, causing heavy cache bounce and overhead. Change them to percpu_counter greatly improve the performance. Since there is one percpu struct per namespace, additional memory cost is minimal. Reading of the count done in msgctl call, which is infrequent. So the need to sum up the counts in each CPU is infrequent. Apply the patch and test the pts/stress-ng-1.4.0 -- system v message passing (160 threads). Score gain: 3.99x CPU: ICX 8380 x 2 sockets Core number: 40 x 2 physical cores Benchmark: pts/stress-ng-1.4.0 -- system v message passing (160 threads) [akpm@linux-foundation.org: coding-style cleanups] [jiebin.sun@intel.com: avoid negative value by overflow in msginfo] Link: https://lkml.kernel.org/r/20220920150809.4014944-1-jiebin.sun@intel.com [akpm@linux-foundation.org: fix min() warnings] Link: https://lkml.kernel.org/r/20220913192538.3023708-3-jiebin.sun@intel.com Signed-off-by: Jiebin Sun Reviewed-by: Tim Chen Cc: Alexander Mikhalitsyn Cc: Alexey Gladkov Cc: Christoph Lameter Cc: Davidlohr Bueso Cc: Dennis Zhou Cc: "Eric W . Biederman" Cc: Manfred Spraul Cc: Shakeel Butt Cc: Tejun Heo Cc: Vasily Averin Signed-off-by: Andrew Morton --- ipc/msg.c | 48 ++++++++++++++++++++++++++++++++++-------------- 1 file changed, 34 insertions(+), 14 deletions(-) (limited to 'ipc/msg.c') diff --git a/ipc/msg.c b/ipc/msg.c index a0d05775af2c..e4e0990e08f7 100644 --- a/ipc/msg.c +++ b/ipc/msg.c @@ -39,6 +39,7 @@ #include #include #include +#include #include #include @@ -285,10 +286,10 @@ static void freeque(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp) rcu_read_unlock(); list_for_each_entry_safe(msg, t, &msq->q_messages, m_list) { - atomic_dec(&ns->msg_hdrs); + percpu_counter_sub_local(&ns->percpu_msg_hdrs, 1); free_msg(msg); } - atomic_sub(msq->q_cbytes, &ns->msg_bytes); + percpu_counter_sub_local(&ns->percpu_msg_bytes, msq->q_cbytes); ipc_update_pid(&msq->q_lspid, NULL); ipc_update_pid(&msq->q_lrpid, NULL); ipc_rcu_putref(&msq->q_perm, msg_rcu_free); @@ -495,17 +496,22 @@ static int msgctl_info(struct ipc_namespace *ns, int msqid, msginfo->msgssz = MSGSSZ; msginfo->msgseg = MSGSEG; down_read(&msg_ids(ns).rwsem); - if (cmd == MSG_INFO) { + if (cmd == MSG_INFO) msginfo->msgpool = msg_ids(ns).in_use; - msginfo->msgmap = atomic_read(&ns->msg_hdrs); - msginfo->msgtql = atomic_read(&ns->msg_bytes); + max_idx = ipc_get_maxidx(&msg_ids(ns)); + up_read(&msg_ids(ns).rwsem); + if (cmd == MSG_INFO) { + msginfo->msgmap = min_t(int, + percpu_counter_sum(&ns->percpu_msg_hdrs), + INT_MAX); + msginfo->msgtql = min_t(int, + percpu_counter_sum(&ns->percpu_msg_bytes), + INT_MAX); } else { msginfo->msgmap = MSGMAP; msginfo->msgpool = MSGPOOL; msginfo->msgtql = MSGTQL; } - max_idx = ipc_get_maxidx(&msg_ids(ns)); - up_read(&msg_ids(ns).rwsem); return (max_idx < 0) ? 0 : max_idx; } @@ -935,8 +941,8 @@ static long do_msgsnd(int msqid, long mtype, void __user *mtext, list_add_tail(&msg->m_list, &msq->q_messages); msq->q_cbytes += msgsz; msq->q_qnum++; - atomic_add(msgsz, &ns->msg_bytes); - atomic_inc(&ns->msg_hdrs); + percpu_counter_add_local(&ns->percpu_msg_bytes, msgsz); + percpu_counter_add_local(&ns->percpu_msg_hdrs, 1); } err = 0; @@ -1159,8 +1165,8 @@ static long do_msgrcv(int msqid, void __user *buf, size_t bufsz, long msgtyp, in msq->q_rtime = ktime_get_real_seconds(); ipc_update_pid(&msq->q_lrpid, task_tgid(current)); msq->q_cbytes -= msg->m_ts; - atomic_sub(msg->m_ts, &ns->msg_bytes); - atomic_dec(&ns->msg_hdrs); + percpu_counter_sub_local(&ns->percpu_msg_bytes, msg->m_ts); + percpu_counter_sub_local(&ns->percpu_msg_hdrs, 1); ss_wakeup(msq, &wake_q, false); goto out_unlock0; @@ -1297,20 +1303,34 @@ COMPAT_SYSCALL_DEFINE5(msgrcv, int, msqid, compat_uptr_t, msgp, } #endif -void msg_init_ns(struct ipc_namespace *ns) +int msg_init_ns(struct ipc_namespace *ns) { + int ret; + ns->msg_ctlmax = MSGMAX; ns->msg_ctlmnb = MSGMNB; ns->msg_ctlmni = MSGMNI; - atomic_set(&ns->msg_bytes, 0); - atomic_set(&ns->msg_hdrs, 0); + ret = percpu_counter_init(&ns->percpu_msg_bytes, 0, GFP_KERNEL); + if (ret) + goto fail_msg_bytes; + ret = percpu_counter_init(&ns->percpu_msg_hdrs, 0, GFP_KERNEL); + if (ret) + goto fail_msg_hdrs; ipc_init_ids(&ns->ids[IPC_MSG_IDS]); + return 0; + +fail_msg_hdrs: + percpu_counter_destroy(&ns->percpu_msg_bytes); +fail_msg_bytes: + return ret; } #ifdef CONFIG_IPC_NS void msg_exit_ns(struct ipc_namespace *ns) { + percpu_counter_destroy(&ns->percpu_msg_bytes); + percpu_counter_destroy(&ns->percpu_msg_hdrs); free_ipcs(ns, &msg_ids(ns), freeque); idr_destroy(&ns->ids[IPC_MSG_IDS].ipcs_idr); rhashtable_destroy(&ns->ids[IPC_MSG_IDS].key_ht); -- cgit v1.2.3