All of lore.kernel.org
 help / color / mirror / Atom feed
From: Joel Fernandes <joel@joelfernandes.org>
To: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: linux-kernel@vger.kernel.org, mingo@kernel.org,
	jiangshanlai@gmail.com, dipankar@in.ibm.com,
	akpm@linux-foundation.org, mathieu.desnoyers@efficios.com,
	josh@joshtriplett.org, tglx@linutronix.de, peterz@infradead.org,
	rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com,
	fweisbec@gmail.com, oleg@redhat.com, joel.opensrc@gmail.com,
	torvalds@linux-foundation.org, npiggin@gmail.com
Subject: Re: [tip/core/rcu, 05/21] rcu: Make rcu_gp_cleanup() more accurately predict need for new GP
Date: Thu, 10 May 2018 10:37:54 -0700	[thread overview]
Message-ID: <20180510173754.GB228531@joelaf.mtv.corp.google.com> (raw)
In-Reply-To: <20180510131546.GN26088@linux.vnet.ibm.com>

On Thu, May 10, 2018 at 06:15:46AM -0700, Paul E. McKenney wrote:
[...] 
> > Also in rcu_future_gp_cleanup, we call:
> > 	trace_rcu_future_gp(rnp, rdp, c,
> > 			    needmore ? TPS("CleanupMore") : TPS("Cleanup"));
> > For this case, in the final trace event record, rnp->completed and c will be
> > the same, since c is set to rnp->completed before calling
> > trace_rcu_future_gp. I was thinking they should be different, do you expect
> > them to be the same?
> 
> Hmmm...  That does look a bit inconsistent.  And it currently uses
> rnp->gp_seq instead of rnp->gp_seq_needed despite having the same
> "CleanupMore" name.
> 
> Looks like a review of the calls to trace_rcu_this_gp() is in order.

I see you changed trace_rcu_future_gp to use trace_rcu_this_gp in 15/21.. I
am not sure if the concern is still valid then since you seem to be correctly
getting the future GP in those cases, except for the naming which I suggest
be changed from 'c' to 'future_gp' just for clarity / self-documenting code.

thanks,

- Joel
 

  parent reply	other threads:[~2018-05-10 17:37 UTC|newest]

Thread overview: 44+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-23  3:02 [PATCH tip/core/rcu 0/21] Contention reduction for v4.18 Paul E. McKenney
2018-04-23  3:03 ` [PATCH tip/core/rcu 01/21] rcu: Improve non-root rcu_cbs_completed() accuracy Paul E. McKenney
2018-04-23  3:03 ` [PATCH tip/core/rcu 02/21] rcu: Make rcu_start_future_gp()'s grace-period check more precise Paul E. McKenney
2018-04-23  3:03 ` [PATCH tip/core/rcu 03/21] rcu: Add accessor macros for the ->need_future_gp[] array Paul E. McKenney
2018-04-23  3:03 ` [PATCH tip/core/rcu 04/21] rcu: Make rcu_gp_kthread() check for early-boot activity Paul E. McKenney
2018-04-23  3:03 ` [PATCH tip/core/rcu 05/21] rcu: Make rcu_gp_cleanup() more accurately predict need for new GP Paul E. McKenney
2018-05-10  7:21   ` [tip/core/rcu, " Joel Fernandes
2018-05-10 13:15     ` Paul E. McKenney
2018-05-10 17:22       ` Joel Fernandes
2018-05-11 16:22         ` Paul E. McKenney
2018-05-10 17:37       ` Joel Fernandes [this message]
2018-05-11 16:24         ` Paul E. McKenney
2018-05-11 16:27           ` Joel Fernandes
2018-04-23  3:03 ` [PATCH tip/core/rcu 06/21] rcu: Avoid losing ->need_future_gp[] values due to GP start/end races Paul E. McKenney
2018-04-23  3:03 ` [PATCH tip/core/rcu 07/21] rcu: Make rcu_future_needs_gp() check all ->need_future_gps[] elements Paul E. McKenney
2018-04-23  3:03 ` [PATCH tip/core/rcu 08/21] rcu: Convert ->need_future_gp[] array to boolean Paul E. McKenney
2018-04-23  3:03 ` [PATCH tip/core/rcu 09/21] rcu: Make rcu_migrate_callbacks wake GP kthread when needed Paul E. McKenney
2018-04-23  3:03 ` [PATCH tip/core/rcu 10/21] rcu: Avoid __call_rcu_core() root rcu_node ->lock acquisition Paul E. McKenney
2018-04-23  3:03 ` [PATCH tip/core/rcu 11/21] rcu: Switch __rcu_process_callbacks() to rcu_accelerate_cbs() Paul E. McKenney
2018-04-23  3:03 ` [PATCH tip/core/rcu 12/21] rcu: Cleanup, don't put ->completed into an int Paul E. McKenney
2018-04-23  3:03 ` [PATCH tip/core/rcu 13/21] rcu: Clear request other than RCU_GP_FLAG_INIT at GP end Paul E. McKenney
2018-04-23  3:03 ` [PATCH tip/core/rcu 14/21] rcu: Inline rcu_start_gp_advanced() into rcu_start_future_gp() Paul E. McKenney
2018-04-23  3:03 ` [PATCH tip/core/rcu 15/21] rcu: Make rcu_start_future_gp() caller select grace period Paul E. McKenney
2018-04-23  3:03 ` [PATCH tip/core/rcu 16/21] rcu: Add funnel locking to rcu_start_this_gp() Paul E. McKenney
2018-05-12  6:03   ` [tip/core/rcu,16/21] " Joel Fernandes
2018-05-12 14:40     ` Paul E. McKenney
2018-05-12 14:44       ` Paul E. McKenney
2018-05-12 23:53         ` Joel Fernandes
2018-05-13 15:38           ` Paul E. McKenney
2018-05-13 16:49             ` Joel Fernandes
2018-05-13 19:09               ` Paul E. McKenney
2018-05-13 19:51                 ` Joel Fernandes
2018-05-14  2:22                   ` Paul E. McKenney
2018-05-14  5:00                     ` Joel Fernandes
2018-05-14 13:23                       ` Paul E. McKenney
2018-04-23  3:03 ` [PATCH tip/core/rcu 17/21] rcu: Make rcu_start_this_gp() check for out-of-range requests Paul E. McKenney
2018-04-23  3:03 ` [PATCH tip/core/rcu 18/21] rcu: The rcu_gp_cleanup() function does not need cpu_needs_another_gp() Paul E. McKenney
2018-04-23  3:03 ` [PATCH tip/core/rcu 19/21] rcu: Simplify and inline cpu_needs_another_gp() Paul E. McKenney
2018-04-23  3:03 ` [PATCH tip/core/rcu 20/21] rcu: Drop early GP request check from rcu_gp_kthread() Paul E. McKenney
2018-04-23  3:03 ` [PATCH tip/core/rcu 21/21] rcu: Update list of rcu_future_grace_period() trace events Paul E. McKenney
2018-05-14  6:42 ` [PATCH tip/core/rcu 0/21] Contention reduction for v4.18 Nicholas Piggin
2018-05-14 16:09   ` Paul E. McKenney
2018-05-14 22:21     ` Nicholas Piggin
2018-05-14 22:42       ` Paul E. McKenney

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20180510173754.GB228531@joelaf.mtv.corp.google.com \
    --to=joel@joelfernandes.org \
    --cc=akpm@linux-foundation.org \
    --cc=dhowells@redhat.com \
    --cc=dipankar@in.ibm.com \
    --cc=edumazet@google.com \
    --cc=fweisbec@gmail.com \
    --cc=jiangshanlai@gmail.com \
    --cc=joel.opensrc@gmail.com \
    --cc=josh@joshtriplett.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mathieu.desnoyers@efficios.com \
    --cc=mingo@kernel.org \
    --cc=npiggin@gmail.com \
    --cc=oleg@redhat.com \
    --cc=paulmck@linux.vnet.ibm.com \
    --cc=peterz@infradead.org \
    --cc=rostedt@goodmis.org \
    --cc=tglx@linutronix.de \
    --cc=torvalds@linux-foundation.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.