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[36.225.97.241]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2b5fa9fedf0sm127474425ad.6.2026.04.20.08.24.01 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 20 Apr 2026 08:24:03 -0700 (PDT) Date: Mon, 20 Apr 2026 23:23:59 +0800 From: Cheng-Yang Chou To: Kuba Piecuch Cc: Tejun Heo , Andrea Righi , Changwoo Min , David Vernet , linux-kernel@vger.kernel.org, sched-ext@lists.linux.dev, Ching-Chun Huang , Chia-Ping Tsai Subject: Re: [PATCH] sched_ext: Documentation: add note about multiple ops.enqueue() calls in a row Message-ID: <20260420232245.Gc8ef@cchengyang.duckdns.org> References: <20260420143939.3636883-1-jpiecuch@google.com> <20260420230420.G737d@cchengyang.duckdns.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Hi Kuba, On Mon, Apr 20, 2026 at 03:21:59PM +0000, Kuba Piecuch wrote: > Hi Cheng-Yang, > > On Mon Apr 20, 2026 at 3:12 PM UTC, Cheng-Yang Chou wrote: > > Hi Kuba, > > > > On Mon, Apr 20, 2026 at 02:39:39PM +0000, Kuba Piecuch wrote: > >> Commit 84b1a0ea0b7c > >> ("sched_ext: Implement scx_bpf_dsq_reenq() for user DSQs") > >> introduced the possibility of ops.enqueue() being called multiple times > >> in a row for the same task without intervening calls to ops.dequeue(). > >> AFAIK this was not possible before that commit. > > ^^^^^ > > Nit: Do we really need this line in the commit message? > > Perhaps we can just drop this? > > I put it there just in case someone was actually aware of a scenario before > that commit where we can have multiple ops.enqueue() calls in a row. I see, thanks! > > Regarding removing the line: yeah, I guess it's a bit redundant. > I'll send a v2. > > > > >> Document this behavior as it may be surprising to some. > >> > >> Signed-off-by: Kuba Piecuch > >> --- > >> Documentation/scheduler/sched-ext.rst | 5 +++++ > >> 1 file changed, 5 insertions(+) > >> > >> diff --git a/Documentation/scheduler/sched-ext.rst b/Documentation/scheduler/sched-ext.rst > >> index 03d595d178ea..fba09aa1cd4e 100644 > >> --- a/Documentation/scheduler/sched-ext.rst > >> +++ b/Documentation/scheduler/sched-ext.rst > >> @@ -339,6 +339,11 @@ The following briefly shows how a waking task is scheduled and executed. > >> leaves (e.g., when ``ops.dispatch()`` moves it to a terminal DSQ, or > >> on property change / sleep). > >> > >> + Note that ``ops.enqueue()`` can be called multiple times in a row without > >> + an intervening call to ``ops.dequeue()``. This can happen, for example, > >> + when a task on a user-created DSQ is re-enqueued using > >> + ``scx_bpf_dsq_reenq()``. The task stays in BPF custody the entire time. > >> + > > > > Thanks for adding and clarifying this. ^v^ > > > > Acked-by: Cheng-Yang Chou > > > > Thanks, > Kuba -- Cheers, Cheng-Yang