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McKenney" To: Joel Fernandes Cc: linux-kernel@vger.kernel.org, kernel-team@android.com, Ingo Molnar , Josh Triplett , Lai Jiangshan , Mathieu Desnoyers , Peter Zijlstra , Steven Rostedt Subject: Re: [PATCH RFC 1/2] sched/core: Convert synchronize_rcu_mult to synchronize_rcu Reply-To: paulmck@linux.ibm.com References: <20181002012012.13133-1-joel@joelfernandes.org> <20181002033801.GP4222@linux.ibm.com> <20181002212019.GC89166@joelaf.mtv.corp.google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181002212019.GC89166@joelaf.mtv.corp.google.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-GCONF: 00 x-cbid: 18100222-0068-0000-0000-000003464D64 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00009811; HX=3.00000242; KW=3.00000007; PH=3.00000004; SC=3.00000267; SDB=6.01096972; UDB=6.00567268; IPR=6.00877014; MB=3.00023593; MTD=3.00000008; XFM=3.00000015; UTC=2018-10-02 22:07:51 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18100222-0069-0000-0000-000045EF5AFB Message-Id: <20181002220748.GM4222@linux.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2018-10-02_09:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1807170000 definitions=main-1810020205 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Oct 02, 2018 at 02:20:19PM -0700, Joel Fernandes wrote: > On Mon, Oct 01, 2018 at 08:38:01PM -0700, Paul E. McKenney wrote: > > On Mon, Oct 01, 2018 at 06:20:11PM -0700, Joel Fernandes wrote: > > > From: "Joel Fernandes (Google)" > > > > > > synchronize_rcu_mult is now obsolete since all the different RCU flavors > > > have been consolidated and the API is now common on the updater side. > > > sched/core.c is the only user of it. All call_rcu_ calls boil > > > down to the same call_rcu. So there's no point in calling > > > synchronize_rcu_mult infact it could potentially be slower due to > > > waiting for the call_rcu callback twice. Just call synchronize_rcu here > > > which should do the job. > > > > > > Signed-off-by: Joel Fernandes (Google) > > > > Well, the theory was that I was going to keep this series hidden until > > the consolidation hit mainline just to avoid confusion, but please see > > 5fc9d4e000b1 ("rcu: Eliminate synchronize_rcu_mult()"), which I just > > now pushed to -rcu. To your credit, you did get most of it. ;-) > > Glad you already took care of that ;-) I should have taken a peek at rcu/test > branch :D You wouldn't have seen anything before yesterday, so no worries! > > Here is the full list: > > > > pick 1f3e6eaed8fa Apply coccinelle script to consolidate calls to RCU-bh and RCU-sched > > pick 5fc9d4e000b1 rcu: Eliminate synchronize_rcu_mult() > > pick a8475496801e rcu: Consolidate the RCU update functions invoked by sync.c > > pick d8ffb03461ad sched/membarrier: Replace synchronize_sched() with synchronize_rcu() > > > > Of course, I will need to rerun the coccinelle script and split the > > result across subsystems, but I am waiting until the current pull > > request hits mainline. Let's face it, none of us need to do debugging > > on someone consolidating their RCU updates before at least this commit > > and its predecessors hit mainline: > > > > 709fdce7545c ("rcu: Express Tiny RCU updates in terms of RCU rather than RCU-sched") > > > > I sent the pull request to Ingo a few days ago, so with some luck this > > will all get to mainline during the next merge window, and then it is > > open season on outside-of-RCU cleanups. ;-) > > Cool, thanks, And Ingo did pull it, and you should have been CCed on a few of the -tip notifications. ;-) Thanx, Paul