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boundary="-----BtiRfIwJ_n6lLjqSnW_hkHVJs.G1Q1_quieK.Ms.6zkUSMJ=_1a0a7b_" X-Sendblock-Type: AUTO_CONFIDENTIAL CMS-TYPE: 102P X-ArchiveUser: EV DLP-Filter: Pass X-CFilter-Loop: Reflected X-CMS-RootMailID: 20230901010734epcas2p1a0d3698e76590637f9175fca40ad9eaf References: <20230901010704.18493-1-bongkyu7.kim@samsung.com> <20230901010704.18493-2-bongkyu7.kim@samsung.com> <20230904151008.GA25717@noisy.programming.kicks-ass.net> <94764456-c4d4-03eb-81ef-df402f4916f6@redhat.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org -------BtiRfIwJ_n6lLjqSnW_hkHVJs.G1Q1_quieK.Ms.6zkUSMJ=_1a0a7b_ Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline On Mon, Sep 04, 2023 at 03:56:56PM -0400, Waiman Long wrote: > On 9/4/23 11:10, Peter Zijlstra wrote: > > On Fri, Sep 01, 2023 at 10:07:03AM +0900, Bongkyu Kim wrote: > > > This reverts commit 617f3ef95177840c77f59c2aec1029d27d5547d6. > > > > > > In mobile environment, reader optimistic spinning is still useful > > > because there're not many readers. In my test result at android device, > > > it improves application startup time about 3.8% > > > App startup time is most important factor for android user expriences. > > > So, re-enable reader optimistic spinning by this commit. And, > > > the later patch will make it optional feature by cmdline. > > I'm not seeing any mention on how this interacts with all the rwsem work > > that has been done since that commit, like the handoff rework. > > > > Why is a straight revert a sane thing at this point? > > I also agree that a revert is not the best way to reintroduce the feature. > It should document the reason why reader optimistic spinning is not the > default as discussed in commit 617f3ef9517 ("locking/rwsem: Remove reader > optimistic spinning") and under what condition should reader optimistic > spinning can be turned back on. > > Besides, I now think we may not really need 2 separate nonspinnable bits. We > can go with one that is set by writer timing out when spinning on reader. > > Cheers, > Longman Should I modify like the below? - Title to "locking/rwsem: Reintroduce reader optimistic spinning" - Add more document like Longman's comment - Reconsidering about 2 separate nonspinnable bits to one Thanks, Bongkyu -------BtiRfIwJ_n6lLjqSnW_hkHVJs.G1Q1_quieK.Ms.6zkUSMJ=_1a0a7b_ Content-Type: text/plain; charset="utf-8" -------BtiRfIwJ_n6lLjqSnW_hkHVJs.G1Q1_quieK.Ms.6zkUSMJ=_1a0a7b_--