linux-kernel - Re: [PATCH v7 02/11] rcu: Make call

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <Yzwb8vgYhAvDJzK+@pc636>
Date:   Tue, 4 Oct 2022 13:41:38 +0200
From:   Uladzislau Rezki <urezki@...il.com>
To:     paulmck@...nel.org,
        "Joel Fernandes (Google)" <joel@...lfernandes.org>
Cc:     rcu@...r.kernel.org, linux-kernel@...r.kernel.org,
        rushikesh.s.kadam@...el.com, urezki@...il.com,
        neeraj.iitr10@...il.com, frederic@...nel.org, paulmck@...nel.org,
        rostedt@...dmis.org, youssefesmat@...gle.com, surenb@...gle.com
Subject: Re: [PATCH v7 02/11] rcu: Make call_rcu() lazy to save power

>  		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