lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
Open Source and information security mailing list archives
| ||
|
Message-Id: <1356799386-4212-8-git-send-email-fweisbec@gmail.com> Date: Sat, 29 Dec 2012 17:42:46 +0100 From: Frederic Weisbecker <fweisbec@...il.com> To: LKML <linux-kernel@...r.kernel.org> Cc: Frederic Weisbecker <fweisbec@...il.com>, Alessio Igor Bogani <abogani@...nel.org>, Andrew Morton <akpm@...ux-foundation.org>, Chris Metcalf <cmetcalf@...era.com>, Christoph Lameter <cl@...ux.com>, Geoff Levand <geoff@...radead.org>, Gilad Ben Yossef <gilad@...yossef.com>, Hakan Akkan <hakanakkan@...il.com>, Ingo Molnar <mingo@...nel.org>, "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>, Paul Gortmaker <paul.gortmaker@...driver.com>, Peter Zijlstra <peterz@...radead.org>, Thomas Gleixner <tglx@...utronix.de>, Steven Rostedt <rostedt@...dmis.org> Subject: [PATCH 07/27] nohz: Assign timekeeping duty to a non-full-nohz CPU This way the full nohz CPUs can safely run with the tick stopped with a guarantee that somebody else is taking care of the jiffies and gtod progression. NOTE: this doesn't handle CPU hotplug. Also we could use something more elaborated wrt. powersaving if we have more than one non full-nohz CPU running. But let's use this KISS solution for now. Signed-off-by: Frederic Weisbecker <fweisbec@...il.com> Cc: Alessio Igor Bogani <abogani@...nel.org> Cc: Andrew Morton <akpm@...ux-foundation.org> Cc: Chris Metcalf <cmetcalf@...era.com> Cc: Christoph Lameter <cl@...ux.com> Cc: Geoff Levand <geoff@...radead.org> Cc: Gilad Ben Yossef <gilad@...yossef.com> Cc: Hakan Akkan <hakanakkan@...il.com> Cc: Ingo Molnar <mingo@...nel.org> Cc: Paul E. McKenney <paulmck@...ux.vnet.ibm.com> Cc: Paul Gortmaker <paul.gortmaker@...driver.com> Cc: Peter Zijlstra <peterz@...radead.org> Cc: Thomas Gleixner <tglx@...utronix.de> [fix have_nohz_full_mask offcase] Signed-off-by: Steven Rostedt <rostedt@...dmis.org> --- kernel/time/tick-broadcast.c | 3 ++- kernel/time/tick-common.c | 5 ++++- kernel/time/tick-sched.c | 9 ++++++++- 3 files changed, 14 insertions(+), 3 deletions(-) diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c index f113755..596c547 100644 --- a/kernel/time/tick-broadcast.c +++ b/kernel/time/tick-broadcast.c @@ -537,7 +537,8 @@ void tick_broadcast_setup_oneshot(struct clock_event_device *bc) bc->event_handler = tick_handle_oneshot_broadcast; /* Take the do_timer update */ - tick_do_timer_cpu = cpu; + if (!tick_nohz_full_cpu(cpu)) + tick_do_timer_cpu = cpu; /* * We must be careful here. There might be other CPUs diff --git a/kernel/time/tick-common.c b/kernel/time/tick-common.c index b1600a6..83f2bd9 100644 --- a/kernel/time/tick-common.c +++ b/kernel/time/tick-common.c @@ -163,7 +163,10 @@ static void tick_setup_device(struct tick_device *td, * this cpu: */ if (tick_do_timer_cpu == TICK_DO_TIMER_BOOT) { - tick_do_timer_cpu = cpu; + if (!tick_nohz_full_cpu(cpu)) + tick_do_timer_cpu = cpu; + else + tick_do_timer_cpu = TICK_DO_TIMER_NONE; tick_next_period = ktime_get(); tick_period = ktime_set(0, NSEC_PER_SEC / HZ); } diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index fac9ba4..f19e8bf 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -112,7 +112,8 @@ static void tick_sched_do_timer(ktime_t now) * this duty, then the jiffies update is still serialized by * jiffies_lock. */ - if (unlikely(tick_do_timer_cpu == TICK_DO_TIMER_NONE)) + if (unlikely(tick_do_timer_cpu == TICK_DO_TIMER_NONE) + && !tick_nohz_full_cpu(cpu)) tick_do_timer_cpu = cpu; #endif @@ -163,6 +164,8 @@ static int __init tick_nohz_full_setup(char *str) return 1; } __setup("full_nohz=", tick_nohz_full_setup); +#else +#define have_full_nohz_mask (0) #endif /* @@ -512,6 +515,10 @@ static bool can_stop_idle_tick(int cpu, struct tick_sched *ts) return false; } + /* If there are full nohz CPUs around, we need to keep the timekeeping duty */ + if (have_full_nohz_mask && tick_do_timer_cpu == cpu) + return false; + return true; } -- 1.7.5.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists