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author | 2019-11-05 08:31:56 -0800 | |
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committer | 2019-12-09 13:00:27 -0800 | |
commit | a289e608b3e740c15f623148c26cdec2d6698ce0 (patch) | |
tree | 81d958fce94e9ee90824d92d63d5bd28d874d198 | |
parent | rcutorture: Add worst-case call_rcu() forward-progress results (diff) | |
download | linux-a289e608b3e740c15f623148c26cdec2d6698ce0.tar.gz linux-a289e608b3e740c15f623148c26cdec2d6698ce0.tar.bz2 linux-a289e608b3e740c15f623148c26cdec2d6698ce0.zip |
rcutorture: Pull callback forward-progress data into rcu_fwd struct
Now that RCU behaves reasonably well with the current single-kthread
call_rcu() forward-progress testing, it is time to add more kthreads.
This commit takes a first step towards that goal by wrapping what
will be the per-kthread data into a new rcu_fwd structure.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
-rw-r--r-- | kernel/rcu/rcutorture.c | 103 |
1 files changed, 58 insertions, 45 deletions
diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c index dee043feb71f..22a75a4b6b40 100644 --- a/kernel/rcu/rcutorture.c +++ b/kernel/rcu/rcutorture.c @@ -1663,23 +1663,34 @@ struct rcu_fwd_cb { struct rcu_fwd_cb *rfc_next; int rfc_gps; }; -static DEFINE_SPINLOCK(rcu_fwd_lock); -static struct rcu_fwd_cb *rcu_fwd_cb_head; -static struct rcu_fwd_cb **rcu_fwd_cb_tail = &rcu_fwd_cb_head; -static long n_launders_cb; -static unsigned long rcu_fwd_startat; -static bool rcu_fwd_emergency_stop; + #define MAX_FWD_CB_JIFFIES (8 * HZ) /* Maximum CB test duration. */ #define MIN_FWD_CB_LAUNDERS 3 /* This many CB invocations to count. */ #define MIN_FWD_CBS_LAUNDERED 100 /* Number of counted CBs. */ #define FWD_CBS_HIST_DIV 10 /* Histogram buckets/second. */ +#define N_LAUNDERS_HIST (2 * MAX_FWD_CB_JIFFIES / (HZ / FWD_CBS_HIST_DIV)) + struct rcu_launder_hist { long n_launders; unsigned long launder_gp_seq; }; -#define N_LAUNDERS_HIST (2 * MAX_FWD_CB_JIFFIES / (HZ / FWD_CBS_HIST_DIV)) -static struct rcu_launder_hist n_launders_hist[N_LAUNDERS_HIST]; -static unsigned long rcu_launder_gp_seq_start; + +struct rcu_fwd { + spinlock_t rcu_fwd_lock; + struct rcu_fwd_cb *rcu_fwd_cb_head; + struct rcu_fwd_cb **rcu_fwd_cb_tail; + long n_launders_cb; + unsigned long rcu_fwd_startat; + struct rcu_launder_hist n_launders_hist[N_LAUNDERS_HIST]; + unsigned long rcu_launder_gp_seq_start; +}; + +struct rcu_fwd rcu_fwds = { + .rcu_fwd_lock = __SPIN_LOCK_UNLOCKED(rcu_fwds.rcu_fwd_lock), + .rcu_fwd_cb_tail = &rcu_fwds.rcu_fwd_cb_head, +}; + +bool rcu_fwd_emergency_stop; static void rcu_torture_fwd_cb_hist(void) { @@ -1688,16 +1699,17 @@ static void rcu_torture_fwd_cb_hist(void) int i; int j; - for (i = ARRAY_SIZE(n_launders_hist) - 1; i > 0; i--) - if (n_launders_hist[i].n_launders > 0) + for (i = ARRAY_SIZE(rcu_fwds.n_launders_hist) - 1; i > 0; i--) + if (rcu_fwds.n_launders_hist[i].n_launders > 0) break; pr_alert("%s: Callback-invocation histogram (duration %lu jiffies):", - __func__, jiffies - rcu_fwd_startat); - gps_old = rcu_launder_gp_seq_start; + __func__, jiffies - rcu_fwds.rcu_fwd_startat); + gps_old = rcu_fwds.rcu_launder_gp_seq_start; for (j = 0; j <= i; j++) { - gps = n_launders_hist[j].launder_gp_seq; + gps = rcu_fwds.n_launders_hist[j].launder_gp_seq; pr_cont(" %ds/%d: %ld:%ld", - j + 1, FWD_CBS_HIST_DIV, n_launders_hist[j].n_launders, + j + 1, FWD_CBS_HIST_DIV, + rcu_fwds.n_launders_hist[j].n_launders, rcutorture_seq_diff(gps, gps_old)); gps_old = gps; } @@ -1714,17 +1726,17 @@ static void rcu_torture_fwd_cb_cr(struct rcu_head *rhp) rfcp->rfc_next = NULL; rfcp->rfc_gps++; - spin_lock_irqsave(&rcu_fwd_lock, flags); - rfcpp = rcu_fwd_cb_tail; - rcu_fwd_cb_tail = &rfcp->rfc_next; + spin_lock_irqsave(&rcu_fwds.rcu_fwd_lock, flags); + rfcpp = rcu_fwds.rcu_fwd_cb_tail; + rcu_fwds.rcu_fwd_cb_tail = &rfcp->rfc_next; WRITE_ONCE(*rfcpp, rfcp); - WRITE_ONCE(n_launders_cb, n_launders_cb + 1); - i = ((jiffies - rcu_fwd_startat) / (HZ / FWD_CBS_HIST_DIV)); - if (i >= ARRAY_SIZE(n_launders_hist)) - i = ARRAY_SIZE(n_launders_hist) - 1; - n_launders_hist[i].n_launders++; - n_launders_hist[i].launder_gp_seq = cur_ops->get_gp_seq(); - spin_unlock_irqrestore(&rcu_fwd_lock, flags); + WRITE_ONCE(rcu_fwds.n_launders_cb, rcu_fwds.n_launders_cb + 1); + i = ((jiffies - rcu_fwds.rcu_fwd_startat) / (HZ / FWD_CBS_HIST_DIV)); + if (i >= ARRAY_SIZE(rcu_fwds.n_launders_hist)) + i = ARRAY_SIZE(rcu_fwds.n_launders_hist) - 1; + rcu_fwds.n_launders_hist[i].n_launders++; + rcu_fwds.n_launders_hist[i].launder_gp_seq = cur_ops->get_gp_seq(); + spin_unlock_irqrestore(&rcu_fwds.rcu_fwd_lock, flags); } // Give the scheduler a chance, even on nohz_full CPUs. @@ -1751,16 +1763,16 @@ static unsigned long rcu_torture_fwd_prog_cbfree(void) struct rcu_fwd_cb *rfcp; for (;;) { - spin_lock_irqsave(&rcu_fwd_lock, flags); - rfcp = rcu_fwd_cb_head; + spin_lock_irqsave(&rcu_fwds.rcu_fwd_lock, flags); + rfcp = rcu_fwds.rcu_fwd_cb_head; if (!rfcp) { - spin_unlock_irqrestore(&rcu_fwd_lock, flags); + spin_unlock_irqrestore(&rcu_fwds.rcu_fwd_lock, flags); break; } - rcu_fwd_cb_head = rfcp->rfc_next; - if (!rcu_fwd_cb_head) - rcu_fwd_cb_tail = &rcu_fwd_cb_head; - spin_unlock_irqrestore(&rcu_fwd_lock, flags); + rcu_fwds.rcu_fwd_cb_head = rfcp->rfc_next; + if (!rcu_fwds.rcu_fwd_cb_head) + rcu_fwds.rcu_fwd_cb_tail = &rcu_fwds.rcu_fwd_cb_head; + spin_unlock_irqrestore(&rcu_fwds.rcu_fwd_lock, flags); kfree(rfcp); freed++; rcu_torture_fwd_prog_cond_resched(freed); @@ -1804,8 +1816,8 @@ static void rcu_torture_fwd_prog_nr(int *tested, int *tested_tries) sd = cur_ops->stall_dur() + 1; sd4 = (sd + fwd_progress_div - 1) / fwd_progress_div; dur = sd4 + torture_random(&trs) % (sd - sd4); - WRITE_ONCE(rcu_fwd_startat, jiffies); - stopat = rcu_fwd_startat + dur; + WRITE_ONCE(rcu_fwds.rcu_fwd_startat, jiffies); + stopat = rcu_fwds.rcu_fwd_startat + dur; while (time_before(jiffies, stopat) && !shutdown_time_arrived() && !READ_ONCE(rcu_fwd_emergency_stop) && !torture_must_stop()) { @@ -1864,23 +1876,23 @@ static void rcu_torture_fwd_prog_cr(void) /* Loop continuously posting RCU callbacks. */ WRITE_ONCE(rcu_fwd_cb_nodelay, true); cur_ops->sync(); /* Later readers see above write. */ - WRITE_ONCE(rcu_fwd_startat, jiffies); - stopat = rcu_fwd_startat + MAX_FWD_CB_JIFFIES; + WRITE_ONCE(rcu_fwds.rcu_fwd_startat, jiffies); + stopat = rcu_fwds.rcu_fwd_startat + MAX_FWD_CB_JIFFIES; n_launders = 0; - n_launders_cb = 0; + rcu_fwds.n_launders_cb = 0; // Hoist initialization for multi-kthread n_launders_sa = 0; n_max_cbs = 0; n_max_gps = 0; - for (i = 0; i < ARRAY_SIZE(n_launders_hist); i++) - n_launders_hist[i].n_launders = 0; + for (i = 0; i < ARRAY_SIZE(rcu_fwds.n_launders_hist); i++) + rcu_fwds.n_launders_hist[i].n_launders = 0; cver = READ_ONCE(rcu_torture_current_version); gps = cur_ops->get_gp_seq(); - rcu_launder_gp_seq_start = gps; + rcu_fwds.rcu_launder_gp_seq_start = gps; tick_dep_set_task(current, TICK_DEP_BIT_RCU); while (time_before(jiffies, stopat) && !shutdown_time_arrived() && !READ_ONCE(rcu_fwd_emergency_stop) && !torture_must_stop()) { - rfcp = READ_ONCE(rcu_fwd_cb_head); + rfcp = READ_ONCE(rcu_fwds.rcu_fwd_cb_head); rfcpn = NULL; if (rfcp) rfcpn = READ_ONCE(rfcp->rfc_next); @@ -1888,7 +1900,7 @@ static void rcu_torture_fwd_prog_cr(void) if (rfcp->rfc_gps >= MIN_FWD_CB_LAUNDERS && ++n_max_gps >= MIN_FWD_CBS_LAUNDERED) break; - rcu_fwd_cb_head = rfcpn; + rcu_fwds.rcu_fwd_cb_head = rfcpn; n_launders++; n_launders_sa++; } else { @@ -1910,7 +1922,7 @@ static void rcu_torture_fwd_prog_cr(void) } } stoppedat = jiffies; - n_launders_cb_snap = READ_ONCE(n_launders_cb); + n_launders_cb_snap = READ_ONCE(rcu_fwds.n_launders_cb); cver = READ_ONCE(rcu_torture_current_version) - cver; gps = rcutorture_seq_diff(cur_ops->get_gp_seq(), gps); cur_ops->cb_barrier(); /* Wait for callbacks to be invoked. */ @@ -1921,7 +1933,8 @@ static void rcu_torture_fwd_prog_cr(void) WARN_ON(n_max_gps < MIN_FWD_CBS_LAUNDERED); pr_alert("%s Duration %lu barrier: %lu pending %ld n_launders: %ld n_launders_sa: %ld n_max_gps: %ld n_max_cbs: %ld cver %ld gps %ld\n", __func__, - stoppedat - rcu_fwd_startat, jiffies - stoppedat, + stoppedat - rcu_fwds.rcu_fwd_startat, + jiffies - stoppedat, n_launders + n_max_cbs - n_launders_cb_snap, n_launders, n_launders_sa, n_max_gps, n_max_cbs, cver, gps); @@ -1943,7 +1956,7 @@ static int rcutorture_oom_notify(struct notifier_block *self, WARN(1, "%s invoked upon OOM during forward-progress testing.\n", __func__); rcu_torture_fwd_cb_hist(); - rcu_fwd_progress_check(1 + (jiffies - READ_ONCE(rcu_fwd_startat)) / 2); + rcu_fwd_progress_check(1 + (jiffies - READ_ONCE(rcu_fwds.rcu_fwd_startat)) / 2); WRITE_ONCE(rcu_fwd_emergency_stop, true); smp_mb(); /* Emergency stop before free and wait to avoid hangs. */ pr_info("%s: Freed %lu RCU callbacks.\n", |