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From: Josh Poimboeuf <jpoimboe@redhat.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Frederic Weisbecker <frederic@kernel.org>,
	LKML <linux-kernel@vger.kernel.org>, Mel Gorman <mgorman@suse.de>,
	Michal Hocko <mhocko@kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	"Paul E . McKenney" <paulmck@kernel.org>,
	Ingo Molnar <mingo@redhat.com>, Michal Hocko <mhocko@suse.com>,
	rostedt@goodmis.org, jbaron@akamai.com, ardb@kernel.org
Subject: Re: [RFC PATCH 6/8] preempt/dynamic: Provide preempt_schedule[_notrace]() static calls
Date: Wed, 27 Jan 2021 09:59:14 -0600	[thread overview]
Message-ID: <20210127155914.jfmr4jay47yck5h5@treble> (raw)
In-Reply-To: <YBFODfNZCjA9s0IP@hirez.programming.kicks-ass.net>

On Wed, Jan 27, 2021 at 12:27:09PM +0100, Peter Zijlstra wrote:
> On Wed, Jan 27, 2021 at 10:13:47AM +0100, Peter Zijlstra wrote:
> > On Tue, Jan 26, 2021 at 05:57:30PM -0600, Josh Poimboeuf wrote:
> 
> > > Well, I hate it, but I'm not sure I have any better ideas.  It should be
> > > possible to use kallsyms, instead of the rb-tree/register nonsense.  Not
> > > sure about the performance impact though.  Might be a good reason to
> > > speed up kallsyms!
> > 
> > Oh right, let me see if I can make that work.
> 
> Something like so compiles.. but it does make the whole thing depend on
> KALLSYMS_ALL, which is somewhat yuck.
> 
> Also, kallsyms_lookup_name() is horrible, but not trivial to fix because
> of that compression scheme used.

The KALLSYMS_ALL dependency doesn't bother me personally but I assume
some of the tinyconfig folks might not appreciate it being on
permanently.

Can DEFINE_STATIC_CALL() make the tramp-key association?

e.g. have DEFINE_STATIC_CALL() add an entry to .static_call_tramp_key
which has an array of 

struct static_call_tramp_key {
	unsigned int tramp;  // PC-relative pointer to tramp
	unsigned int key;    // PC-relative pointer to key
}

and then just scan that instead of kallsyms.

-- 
Josh


  reply	other threads:[~2021-01-27 16:05 UTC|newest]

Thread overview: 59+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-18 14:12 [RFC PATCH 0/7] preempt: Tune preemption flavour on boot v4 Frederic Weisbecker
2021-01-18 14:12 ` [RFC PATCH 1/8] static_call/x86: Add __static_call_return0() Frederic Weisbecker
2021-02-08 12:00   ` [tip: sched/core] " tip-bot2 for Peter Zijlstra
2021-02-17 13:17   ` tip-bot2 for Peter Zijlstra
2021-01-18 14:12 ` [RFC PATCH 2/8] static_call: Provide DEFINE_STATIC_CALL_RET0() Frederic Weisbecker
2021-02-08 12:00   ` [tip: sched/core] " tip-bot2 for Frederic Weisbecker
2021-02-17 13:17   ` tip-bot2 for Frederic Weisbecker
2021-01-18 14:12 ` [RFC PATCH 3/8] static_call: Pull some static_call declarations to the type headers Frederic Weisbecker
2021-01-19 10:46   ` Jürgen Groß
2021-02-08 12:00   ` [tip: sched/core] " tip-bot2 for Peter Zijlstra
2021-02-17 13:17   ` tip-bot2 for Peter Zijlstra
2021-01-18 14:12 ` [RFC PATCH 4/8] preempt: Introduce CONFIG_PREEMPT_DYNAMIC Frederic Weisbecker
2021-01-22 16:53   ` Peter Zijlstra
2021-01-28 12:17     ` Frederic Weisbecker
2021-02-08 12:00   ` [tip: sched/core] " tip-bot2 for Michal Hocko
2021-02-17 13:17   ` tip-bot2 for Michal Hocko
2021-01-18 14:12 ` [RFC PATCH 5/8] preempt/dynamic: Provide cond_resched() and might_resched() static calls Frederic Weisbecker
2021-02-08 12:00   ` [tip: sched/core] " tip-bot2 for Peter Zijlstra (Intel)
2021-02-17 13:17   ` tip-bot2 for Peter Zijlstra (Intel)
2021-01-18 14:12 ` [RFC PATCH 6/8] preempt/dynamic: Provide preempt_schedule[_notrace]() " Frederic Weisbecker
2021-01-21 21:58   ` Peter Zijlstra
2021-01-21 22:25     ` Peter Zijlstra
2021-01-22 16:52   ` Peter Zijlstra
2021-01-22 16:57     ` Ard Biesheuvel
2021-01-22 17:08       ` Peter Zijlstra
2021-02-08 12:00         ` [tip: sched/core] sched: Add /debug/sched_preempt tip-bot2 for Peter Zijlstra
2021-02-09 15:45         ` tip-bot2 for Peter Zijlstra
2021-02-17 13:17         ` tip-bot2 for Peter Zijlstra
2021-01-25 23:40     ` [RFC PATCH 6/8] preempt/dynamic: Provide preempt_schedule[_notrace]() static calls Josh Poimboeuf
2021-01-26  9:24       ` Peter Zijlstra
2021-01-26 23:57     ` Josh Poimboeuf
2021-01-27  9:13       ` Peter Zijlstra
2021-01-27 11:27         ` Peter Zijlstra
2021-01-27 15:59           ` Josh Poimboeuf [this message]
2021-01-27 16:19             ` Peter Zijlstra
2021-01-27 16:33               ` Josh Poimboeuf
2021-01-27 18:44                 ` Peter Zijlstra
2021-01-27 19:00                   ` Josh Poimboeuf
2021-01-27 19:02                     ` Josh Poimboeuf
2021-01-27 23:18                       ` Josh Poimboeuf
2021-02-03 14:04                         ` Peter Zijlstra
2021-02-05 15:30                           ` Peter Zijlstra
2021-02-06  2:31                             ` Josh Poimboeuf
2021-02-06  9:03                               ` Peter Zijlstra
2021-02-05 15:22                         ` Peter Zijlstra
2021-02-08 12:00                         ` [tip: sched/core] static_call: Allow module use without exposing static_call_key tip-bot2 for Josh Poimboeuf
2021-02-09 15:45                         ` tip-bot2 for Josh Poimboeuf
2021-02-17 13:17                         ` tip-bot2 for Josh Poimboeuf
2021-02-08 12:00   ` [tip: sched/core] preempt/dynamic: Provide preempt_schedule[_notrace]() static calls tip-bot2 for Peter Zijlstra (Intel)
2021-02-17 13:17   ` tip-bot2 for Peter Zijlstra (Intel)
2021-01-18 14:12 ` [RFC PATCH 7/8] preempt/dynamic: Provide irqentry_exit_cond_resched() static call Frederic Weisbecker
2021-02-08 12:00   ` [tip: sched/core] " tip-bot2 for Peter Zijlstra (Intel)
2021-02-17 13:17   ` tip-bot2 for Peter Zijlstra (Intel)
2021-01-18 14:12 ` [RFC PATCH 8/8] preempt/dynamic: Support dynamic preempt with preempt= boot option Frederic Weisbecker
2021-02-08 12:00   ` [tip: sched/core] " tip-bot2 for Peter Zijlstra (Intel)
2021-02-09 15:45   ` tip-bot2 for Peter Zijlstra (Intel)
2021-02-17 13:17   ` tip-bot2 for Peter Zijlstra (Intel)
2021-01-21 21:22 ` [RFC PATCH 0/7] preempt: Tune preemption flavour on boot v4 Peter Zijlstra
2021-01-22 15:02 ` Paul E. McKenney

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