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From:   Uladzislau Rezki <urezki@gmail.com>
Date:   Tue, 4 Oct 2022 13:41:38 +0200
To:     paulmck@kernel.org,
        "Joel Fernandes (Google)" <joel@joelfernandes.org>
Cc:     rcu@vger.kernel.org, linux-kernel@vger.kernel.org,
        rushikesh.s.kadam@intel.com, urezki@gmail.com,
        neeraj.iitr10@gmail.com, frederic@kernel.org, paulmck@kernel.org,
        rostedt@goodmis.org, youssefesmat@google.com, surenb@google.com
Subject: Re: [PATCH v7 02/11] rcu: Make call_rcu() lazy to save power
Message-ID: <Yzwb8vgYhAvDJzK+@pc636>
References: <20221004024157.2470238-1-joel@joelfernandes.org>
 <20221004024157.2470238-3-joel@joelfernandes.org>
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>  		trace_rcu_nocb_wake(rcu_state.name, rdp->cpu, TPS("Check"));
>  		rcu_nocb_lock_irqsave(rdp, flags);
>  		lockdep_assert_held(&rdp->nocb_lock);
>  		bypass_ncbs = rcu_cblist_n_cbs(&rdp->nocb_bypass);
> -		if (bypass_ncbs &&
> +		lazy_ncbs = READ_ONCE(rdp->lazy_len);
> +
> +		if (bypass_ncbs && (lazy_ncbs == bypass_ncbs) &&
> +		    (time_after(j, READ_ONCE(rdp->nocb_bypass_first) + jiffies_till_flush) ||
> +		     bypass_ncbs > 2 * qhimark)) {
Do you know why we want double "qhimark" threshold? It is not only this
place, there are several. I am asking because it is not expected by the
user.

--
Uladzsislau Rezki