From: josh@joshtriplett.org
To: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: linux-kernel@vger.kernel.org, mingo@kernel.org,
laijs@cn.fujitsu.com, dipankar@in.ibm.com,
akpm@linux-foundation.org, mathieu.desnoyers@efficios.com,
niv@us.ibm.com, tglx@linutronix.de, peterz@infradead.org,
rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com,
dvhart@linux.intel.com, fweisbec@gmail.com, oleg@redhat.com,
sbw@mit.edu
Subject: Re: [PATCH tip/core/rcu 0/5] Fix for cond_resched performance regression
Date: Fri, 20 Jun 2014 14:24:23 -0700 [thread overview]
Message-ID: <20140620212423.GA22886@cloud> (raw)
In-Reply-To: <20140620191236.GA10340@linux.vnet.ibm.com>
On Fri, Jun 20, 2014 at 12:12:36PM -0700, Paul E. McKenney wrote:
> o Make cond_resched() a no-op for PREEMPT=y. This might well turn
> out to be a good thing, but it doesn't help give RCU the quiescent
> states that it needs.
What about doing this, together with letting the fqs logic poke
un-quiesced kernel code as needed? That way, rather than having
cond_resched do any work, you have the fqs logic recognize that a
particular CPU has gone too long without quiescing, without disturbing
that CPU at all if it hasn't gone too long.
- Josh Triplett
next prev parent reply other threads:[~2014-06-20 21:24 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-06-20 18:32 [PATCH tip/core/rcu 0/5] Fix for cond_resched performance regression Paul E. McKenney
2014-06-20 18:33 ` [PATCH RFC tip/core/rcu 1/5] rcu: Reduce overhead of cond_resched() checks for RCU Paul E. McKenney
2014-06-20 18:33 ` [PATCH RFC tip/core/rcu 2/5] rcu: Provide cond_resched_rcu_qs() to force quiescent states in long loops Paul E. McKenney
2014-06-20 18:33 ` [PATCH RFC tip/core/rcu 3/5] rcu: Add RCU_COND_RESCHED_QS for large systems Paul E. McKenney
2014-06-20 18:33 ` [PATCH RFC tip/core/rcu 4/5] rcutorture: Suppress spurious RCU CPU stall warnings Paul E. McKenney
2014-06-20 18:33 ` [PATCH RFC tip/core/rcu 5/5] rcu: Add boot/sysfs control for RCU cond_resched() help solicitation Paul E. McKenney
2014-06-23 16:43 ` [PATCH RFC tip/core/rcu 1/5] rcu: Reduce overhead of cond_resched() checks for RCU Oleg Nesterov
2014-06-23 17:36 ` Paul E. McKenney
2014-06-23 18:35 ` Oleg Nesterov
2014-06-24 0:18 ` Paul E. McKenney
2014-07-22 4:35 ` Pranith Kumar
2014-07-22 4:52 ` Pranith Kumar
2014-07-22 11:07 ` Paul E. McKenney
2014-07-22 11:06 ` Paul E. McKenney
2014-06-20 19:04 ` [PATCH tip/core/rcu 0/5] Fix for cond_resched performance regression josh
2014-06-20 22:04 ` Paul E. McKenney
2014-06-20 19:12 ` Paul E. McKenney
2014-06-20 21:24 ` josh [this message]
2014-06-20 22:11 ` Paul E. McKenney
2014-06-20 22:39 ` josh
2014-06-20 23:30 ` Paul E. McKenney
2014-06-20 23:52 ` josh
2014-06-21 0:14 ` Paul E. McKenney
2014-06-21 0:36 ` Paul E. McKenney
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