On Tue, Jan 10, 2006 at 04:48:02PM +0300, Oleg Nesterov wrote:
> This patch moves rcu_state into the rcu_ctrlblk. I think there
> are no reasons why we should have 2 different variables to control
> rcu state. Every user of rcu_state has also "rcu_ctrlblk *rcp" in
> the parameter list.
Looks good to me, passes one-hour RCU torture test.
Manfred, does the ____cacheline_internodealigned_in_smp take care
of your cache-line alignment concerns?
Thanx, Paul
Acked-by: Paul E. McKenney <[email protected]>
> Signed-off-by: Oleg Nesterov <[email protected]>
>
> --- 2.6.15/include/linux/rcupdate.h~3_JOIN 2006-01-10 18:52:29.000000000 +0300
> +++ 2.6.15/include/linux/rcupdate.h 2006-01-10 19:06:38.000000000 +0300
> @@ -65,6 +65,10 @@ struct rcu_ctrlblk {
> long cur; /* Current batch number. */
> long completed; /* Number of the last completed batch */
> int next_pending; /* Is the next batch already waiting? */
> +
> + spinlock_t lock ____cacheline_internodealigned_in_smp;
> + cpumask_t cpumask; /* CPUs that need to switch in order */
> + /* for current batch to proceed. */
> } ____cacheline_internodealigned_in_smp;
>
> /* Is batch a before batch b ? */
> --- 2.6.15/kernel/rcupdate.c~3_JOIN 2006-01-10 18:52:36.000000000 +0300
> +++ 2.6.15/kernel/rcupdate.c 2006-01-10 19:06:38.000000000 +0300
> @@ -49,22 +49,18 @@
> #include <linux/cpu.h>
>
> /* Definition for rcupdate control block. */
> -struct rcu_ctrlblk rcu_ctrlblk =
> - { .cur = -300, .completed = -300 };
> -struct rcu_ctrlblk rcu_bh_ctrlblk =
> - { .cur = -300, .completed = -300 };
> -
> -/* Bookkeeping of the progress of the grace period */
> -struct rcu_state {
> - spinlock_t lock; /* Guard this struct and writes to rcu_ctrlblk */
> - cpumask_t cpumask; /* CPUs that need to switch in order */
> - /* for current batch to proceed. */
> +struct rcu_ctrlblk rcu_ctrlblk = {
> + .cur = -300,
> + .completed = -300,
> + .lock = SPIN_LOCK_UNLOCKED,
> + .cpumask = CPU_MASK_NONE,
> +};
> +struct rcu_ctrlblk rcu_bh_ctrlblk = {
> + .cur = -300,
> + .completed = -300,
> + .lock = SPIN_LOCK_UNLOCKED,
> + .cpumask = CPU_MASK_NONE,
> };
> -
> -static struct rcu_state rcu_state ____cacheline_internodealigned_in_smp =
> - {.lock = SPIN_LOCK_UNLOCKED, .cpumask = CPU_MASK_NONE };
> -static struct rcu_state rcu_bh_state ____cacheline_internodealigned_in_smp =
> - {.lock = SPIN_LOCK_UNLOCKED, .cpumask = CPU_MASK_NONE };
>
> DEFINE_PER_CPU(struct rcu_data, rcu_data) = { 0L };
> DEFINE_PER_CPU(struct rcu_data, rcu_bh_data) = { 0L };
> @@ -220,13 +216,13 @@ static void rcu_do_batch(struct rcu_data
> * This is done by rcu_start_batch. The start is not broadcasted to
> * all cpus, they must pick this up by comparing rcp->cur with
> * rdp->quiescbatch. All cpus are recorded in the
> - * rcu_state.cpumask bitmap.
> + * rcu_ctrlblk.cpumask bitmap.
> * - All cpus must go through a quiescent state.
> * Since the start of the grace period is not broadcasted, at least two
> * calls to rcu_check_quiescent_state are required:
> * The first call just notices that a new grace period is running. The
> * following calls check if there was a quiescent state since the beginning
> - * of the grace period. If so, it updates rcu_state.cpumask. If
> + * of the grace period. If so, it updates rcu_ctrlblk.cpumask. If
> * the bitmap is empty, then the grace period is completed.
> * rcu_check_quiescent_state calls rcu_start_batch(0) to start the next grace
> * period (if necessary).
> @@ -234,9 +230,9 @@ static void rcu_do_batch(struct rcu_data
> /*
> * Register a new batch of callbacks, and start it up if there is currently no
> * active batch and the batch to be registered has not already occurred.
> - * Caller must hold rcu_state.lock.
> + * Caller must hold rcu_ctrlblk.lock.
> */
> -static void rcu_start_batch(struct rcu_ctrlblk *rcp, struct rcu_state *rsp)
> +static void rcu_start_batch(struct rcu_ctrlblk *rcp)
> {
> if (rcp->next_pending &&
> rcp->completed == rcp->cur) {
> @@ -251,11 +247,11 @@ static void rcu_start_batch(struct rcu_c
> /*
> * Accessing nohz_cpu_mask before incrementing rcp->cur needs a
> * Barrier Otherwise it can cause tickless idle CPUs to be
> - * included in rsp->cpumask, which will extend graceperiods
> + * included in rcp->cpumask, which will extend graceperiods
> * unnecessarily.
> */
> smp_mb();
> - cpus_andnot(rsp->cpumask, cpu_online_map, nohz_cpu_mask);
> + cpus_andnot(rcp->cpumask, cpu_online_map, nohz_cpu_mask);
>
> }
> }
> @@ -265,13 +261,13 @@ static void rcu_start_batch(struct rcu_c
> * Clear it from the cpu mask and complete the grace period if it was the last
> * cpu. Start another grace period if someone has further entries pending
> */
> -static void cpu_quiet(int cpu, struct rcu_ctrlblk *rcp, struct rcu_state *rsp)
> +static void cpu_quiet(int cpu, struct rcu_ctrlblk *rcp)
> {
> - cpu_clear(cpu, rsp->cpumask);
> - if (cpus_empty(rsp->cpumask)) {
> + cpu_clear(cpu, rcp->cpumask);
> + if (cpus_empty(rcp->cpumask)) {
> /* batch completed ! */
> rcp->completed = rcp->cur;
> - rcu_start_batch(rcp, rsp);
> + rcu_start_batch(rcp);
> }
> }
>
> @@ -281,7 +277,7 @@ static void cpu_quiet(int cpu, struct rc
> * quiescent cycle, then indicate that it has done so.
> */
> static void rcu_check_quiescent_state(struct rcu_ctrlblk *rcp,
> - struct rcu_state *rsp, struct rcu_data *rdp)
> + struct rcu_data *rdp)
> {
> if (rdp->quiescbatch != rcp->cur) {
> /* start new grace period: */
> @@ -306,15 +302,15 @@ static void rcu_check_quiescent_state(st
> return;
> rdp->qs_pending = 0;
>
> - spin_lock(&rsp->lock);
> + spin_lock(&rcp->lock);
> /*
> * rdp->quiescbatch/rcp->cur and the cpu bitmap can come out of sync
> * during cpu startup. Ignore the quiescent state.
> */
> if (likely(rdp->quiescbatch == rcp->cur))
> - cpu_quiet(rdp->cpu, rcp, rsp);
> + cpu_quiet(rdp->cpu, rcp);
>
> - spin_unlock(&rsp->lock);
> + spin_unlock(&rcp->lock);
> }
>
>
> @@ -335,16 +331,16 @@ static void rcu_move_batch(struct rcu_da
> }
>
> static void __rcu_offline_cpu(struct rcu_data *this_rdp,
> - struct rcu_ctrlblk *rcp, struct rcu_state *rsp, struct rcu_data *rdp)
> + struct rcu_ctrlblk *rcp, struct rcu_data *rdp)
> {
> /* if the cpu going offline owns the grace period
> * we can block indefinitely waiting for it, so flush
> * it here
> */
> - spin_lock_bh(&rsp->lock);
> + spin_lock_bh(&rcp->lock);
> if (rcp->cur != rcp->completed)
> - cpu_quiet(rdp->cpu, rcp, rsp);
> - spin_unlock_bh(&rsp->lock);
> + cpu_quiet(rdp->cpu, rcp);
> + spin_unlock_bh(&rcp->lock);
> rcu_move_batch(this_rdp, rdp->curlist, rdp->curtail);
> rcu_move_batch(this_rdp, rdp->nxtlist, rdp->nxttail);
>
> @@ -354,9 +350,9 @@ static void rcu_offline_cpu(int cpu)
> struct rcu_data *this_rdp = &get_cpu_var(rcu_data);
> struct rcu_data *this_bh_rdp = &get_cpu_var(rcu_bh_data);
>
> - __rcu_offline_cpu(this_rdp, &rcu_ctrlblk, &rcu_state,
> + __rcu_offline_cpu(this_rdp, &rcu_ctrlblk,
> &per_cpu(rcu_data, cpu));
> - __rcu_offline_cpu(this_bh_rdp, &rcu_bh_ctrlblk, &rcu_bh_state,
> + __rcu_offline_cpu(this_bh_rdp, &rcu_bh_ctrlblk,
> &per_cpu(rcu_bh_data, cpu));
> put_cpu_var(rcu_data);
> put_cpu_var(rcu_bh_data);
> @@ -375,7 +371,7 @@ static void rcu_offline_cpu(int cpu)
> * This does the RCU processing work from tasklet context.
> */
> static void __rcu_process_callbacks(struct rcu_ctrlblk *rcp,
> - struct rcu_state *rsp, struct rcu_data *rdp)
> + struct rcu_data *rdp)
> {
> if (rdp->curlist && !rcu_batch_before(rcp->completed, rdp->batch)) {
> *rdp->donetail = rdp->curlist;
> @@ -405,25 +401,23 @@ static void __rcu_process_callbacks(stru
>
> if (!rcp->next_pending) {
> /* and start it/schedule start if it's a new batch */
> - spin_lock(&rsp->lock);
> + spin_lock(&rcp->lock);
> rcp->next_pending = 1;
> - rcu_start_batch(rcp, rsp);
> - spin_unlock(&rsp->lock);
> + rcu_start_batch(rcp);
> + spin_unlock(&rcp->lock);
> }
> } else {
> local_irq_enable();
> }
> - rcu_check_quiescent_state(rcp, rsp, rdp);
> + rcu_check_quiescent_state(rcp, rdp);
> if (rdp->donelist)
> rcu_do_batch(rdp);
> }
>
> static void rcu_process_callbacks(unsigned long unused)
> {
> - __rcu_process_callbacks(&rcu_ctrlblk, &rcu_state,
> - &__get_cpu_var(rcu_data));
> - __rcu_process_callbacks(&rcu_bh_ctrlblk, &rcu_bh_state,
> - &__get_cpu_var(rcu_bh_data));
> + __rcu_process_callbacks(&rcu_ctrlblk, &__get_cpu_var(rcu_data));
> + __rcu_process_callbacks(&rcu_bh_ctrlblk, &__get_cpu_var(rcu_bh_data));
> }
>
> static int __rcu_pending(struct rcu_ctrlblk *rcp, struct rcu_data *rdp)
>
-
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