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McKenney" To: rcu@vger.kernel.org Cc: linux-kernel@vger.kernel.org, kernel-team@meta.com, rostedt@goodmis.org, hch@lst.de, "Paul E. McKenney" Subject: [PATCH RFC rcu 06/19] srcu: Move ->srcu_cb_mutex from srcu_struct to srcu_usage Date: Thu, 23 Mar 2023 17:19:25 -0700 Message-Id: <20230324001938.3443499-6-paulmck@kernel.org> X-Mailer: git-send-email 2.40.0.rc2 In-Reply-To: <3db82572-f156-4a5d-b711-841aa28bd996@paulmck-laptop> References: <3db82572-f156-4a5d-b711-841aa28bd996@paulmck-laptop> MIME-Version: 1.0 X-Spam-Status: No, score=-2.5 required=5.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_MED,SPF_HELO_NONE, SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1761207988522779234?= X-GMAIL-MSGID: =?utf-8?q?1761207988522779234?= This commit moves the ->srcu_cb_mutex field from the srcu_struct structure to the srcu_usage structure to reduce the size of the former in order to improve cache locality. Suggested-by: Christoph Hellwig Signed-off-by: Paul E. McKenney --- include/linux/srcutree.h | 2 +- kernel/rcu/srcutree.c | 6 +++--- 2 files changed, 4 insertions(+), 4 deletions(-) diff --git a/include/linux/srcutree.h b/include/linux/srcutree.h index 72fb01fb2eb5..69d49de87b67 100644 --- a/include/linux/srcutree.h +++ b/include/linux/srcutree.h @@ -65,13 +65,13 @@ struct srcu_usage { struct srcu_node *level[RCU_NUM_LVLS + 1]; /* First node at each level. */ int srcu_size_state; /* Small-to-big transition state. */ + struct mutex srcu_cb_mutex; /* Serialize CB preparation. */ }; /* * Per-SRCU-domain structure, similar in function to rcu_state. */ struct srcu_struct { - struct mutex srcu_cb_mutex; /* Serialize CB preparation. */ spinlock_t __private lock; /* Protect counters and size state. */ struct mutex srcu_gp_mutex; /* Serialize GP work. */ unsigned int srcu_idx; /* Current rdr array element. */ diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c index 2717217de136..6b6d92fe41cf 100644 --- a/kernel/rcu/srcutree.c +++ b/kernel/rcu/srcutree.c @@ -242,7 +242,7 @@ static int init_srcu_struct_fields(struct srcu_struct *ssp, bool is_static) return -ENOMEM; ssp->srcu_sup->srcu_size_state = SRCU_SIZE_SMALL; ssp->srcu_sup->node = NULL; - mutex_init(&ssp->srcu_cb_mutex); + mutex_init(&ssp->srcu_sup->srcu_cb_mutex); mutex_init(&ssp->srcu_gp_mutex); ssp->srcu_idx = 0; ssp->srcu_gp_seq = 0; @@ -861,7 +861,7 @@ static void srcu_gp_end(struct srcu_struct *ssp) int ss_state; /* Prevent more than one additional grace period. */ - mutex_lock(&ssp->srcu_cb_mutex); + mutex_lock(&ssp->srcu_sup->srcu_cb_mutex); /* End the current grace period. */ spin_lock_irq_rcu_node(ssp); @@ -921,7 +921,7 @@ static void srcu_gp_end(struct srcu_struct *ssp) } /* Callback initiation done, allow grace periods after next. */ - mutex_unlock(&ssp->srcu_cb_mutex); + mutex_unlock(&ssp->srcu_sup->srcu_cb_mutex); /* Start a new grace period if needed. */ spin_lock_irq_rcu_node(ssp);