linux-kernel - Re: [PATCH v4 4/4] rcu: Add RCU stall diagnosis information

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Message-ID: <20221104134316.GM5600@paulmck-ThinkPad-P17-Gen-1>
Date:   Fri, 4 Nov 2022 06:43:16 -0700
From:   "Paul E. McKenney" <paulmck@...nel.org>
To:     "Leizhen (ThunderTown)" <thunder.leizhen@...wei.com>
Cc:     Frederic Weisbecker <frederic@...nel.org>,
        Neeraj Upadhyay <quic_neeraju@...cinc.com>,
        Josh Triplett <josh@...htriplett.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        Lai Jiangshan <jiangshanlai@...il.com>,
        Joel Fernandes <joel@...lfernandes.org>, rcu@...r.kernel.org,
        linux-kernel@...r.kernel.org, Robert Elliott <elliott@....com>
Subject: Re: [PATCH v4 4/4] rcu: Add RCU stall diagnosis information

On Fri, Nov 04, 2022 at 11:12:02AM +0800, Leizhen (ThunderTown) wrote:
> 
> 
> On 2022/11/4 10:12, Zhen Lei wrote:
> > diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h
> > index d4a97e40ea9c3e2..44d49819a31f050 100644
> > --- a/kernel/rcu/tree.h
> > +++ b/kernel/rcu/tree.h
> > @@ -158,6 +158,22 @@ union rcu_noqs {
> >  	u16 s; /* Set of bits, aggregate OR here. */
> >  };
> >  
> > +/*
> > + * Record the snapshot of the core stats at 1/2 rcu stall timeout. The member
> > + * gp_seq is used to ensure that all members are updated only once during the
> > + * second half period. The snapshot is taken only if this gp_seq is not equal
> > + * to rdp->gp_seq.
> > + */
> > +struct rcu_snap_record {
> > +	unsigned long	gp_seq;		/* Track rdp->gp_seq counter */
> > +	u64		cputime_irq;	/* Accumulated cputime of hard irqs */
> > +	u64		cputime_softirq;/* Accumulated cputime of soft irqs */
> > +	u64		cputime_system; /* Accumulated cputime of kernel tasks */
> > +	unsigned long	nr_hardirqs;	/* Accumulated number of hard irqs */
> > +	unsigned int	nr_softirqs;	/* Accumulated number of soft irqs */
> > +	unsigned long long nr_csw;	/* Accumulated number of task switches */
> > +};
> > +
> >  /* Per-CPU data for read-copy update. */
> >  struct rcu_data {
> >  	/* 1) quiescent-state and grace-period handling : */
> > @@ -262,6 +278,7 @@ struct rcu_data {
> >  	short rcu_onl_gp_flags;		/* ->gp_flags at last online. */
> >  	unsigned long last_fqs_resched;	/* Time of last rcu_resched(). */
> >  	unsigned long last_sched_clock;	/* Jiffies of last rcu_sched_clock_irq(). */
> > +	struct rcu_snap_record snap_record; /* Snapshot of core stats at 1/2 rcu stall timeout */
> >  
> >  	int cpu;
> >  };
> 
> Sorry, I forgot to update linux-rcu.git. There is a conflict here.
> 
> ----------------
>  	int cpu;
>   };
> ------------should be--------
>  	long lazy_len;			/* Length of buffered lazy callbacks. */
>  	int cpu;
> ----------------

Not a problem!  Looks good otherwise.

So please just rebase your series onto -rcu and repost.

							Thanx, Paul