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From: Steven Rostedt <rostedt@goodmis.org>
To: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Alexei Starovoitov <ast@fb.com>,
	"David S. Miller" <davem@davemloft.net>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Peter Zijlstra <peterz@infradead.org>,
	netdev <netdev@vger.kernel.org>, kernel-team <kernel-team@fb.com>,
	linux-api <linux-api@vger.kernel.org>,
	Josh Poimboeuf <jpoimboe@redhat.com>
Subject: Re: [PATCH v7 bpf-next 06/10] tracepoint: compute num_args at build time
Date: Wed, 28 Mar 2018 15:38:19 -0400	[thread overview]
Message-ID: <20180328153819.654c1600@gandalf.local.home> (raw)
In-Reply-To: <20180328153220.06a132f4@gandalf.local.home>

On Wed, 28 Mar 2018 15:32:20 -0400
Steven Rostedt <rostedt@goodmis.org> wrote:

> -#define __DO_TRACE(tp, proto, args, cond, rcucheck)			\
> +#define __DO_TRACE(name, proto, args, cond, rcucheck)			\
>  	do {								\
>  		struct tracepoint_func *it_func_ptr;			\
>  		void *it_func;						\
> @@ -140,7 +140,7 @@ extern void syscall_unregfunc(void);
>  		if (rcucheck)						\
>  			rcu_irq_enter_irqson();				\
>  		rcu_read_lock_sched_notrace();				\
> -		it_func_ptr = rcu_dereference_sched((tp)->funcs);	\
> +		it_func_ptr = rcu_dereference_sched(__trace_##name##_funcs); \

What we lose in data size, we may make up for in text (which is even
more important). This will remove a dereference in the hot path.

I'll make a few builds and run size on the vmlinux images to see how
this pans out.

-- Steve


>  		if (it_func_ptr) {					\
>  			do {						\

  reply	other threads:[~2018-03-28 19:38 UTC|newest]

Thread overview: 39+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-03-28  2:10 [PATCH v7 bpf-next 00/10] bpf, tracing: introduce bpf raw tracepoints Alexei Starovoitov
2018-03-28  2:10 ` Alexei Starovoitov
2018-03-28  2:10 ` [PATCH v7 bpf-next 01/10] treewide: remove large struct-pass-by-value from tracepoint arguments Alexei Starovoitov
2018-03-28  2:10   ` Alexei Starovoitov
2018-03-28  2:10 ` [PATCH v7 bpf-next 02/10] net/mediatek: disambiguate mt76 vs mt7601u trace events Alexei Starovoitov
2018-03-28  2:10   ` Alexei Starovoitov
2018-03-28  2:10 ` [PATCH v7 bpf-next 03/10] net/mac802154: disambiguate mac80215 vs mac802154 " Alexei Starovoitov
2018-03-28  2:10   ` Alexei Starovoitov
2018-03-28  2:10 ` [PATCH v7 bpf-next 04/10] net/wireless/iwlwifi: fix iwlwifi_dev_ucode_error tracepoint Alexei Starovoitov
2018-03-28  2:10   ` Alexei Starovoitov
2018-03-28  2:11 ` [PATCH v7 bpf-next 05/10] macro: introduce COUNT_ARGS() macro Alexei Starovoitov
2018-03-28  2:11   ` Alexei Starovoitov
2018-03-28  2:11 ` [PATCH v7 bpf-next 06/10] tracepoint: compute num_args at build time Alexei Starovoitov
2018-03-28  2:11   ` Alexei Starovoitov
2018-03-28 13:49   ` Mathieu Desnoyers
2018-03-28 16:43     ` Alexei Starovoitov
2018-03-28 17:04       ` Steven Rostedt
2018-03-28 17:10         ` Alexei Starovoitov
2018-03-28 17:38           ` Steven Rostedt
2018-03-28 18:03             ` Alexei Starovoitov
2018-03-28 18:10               ` Steven Rostedt
2018-03-28 18:19                 ` Alexei Starovoitov
2018-03-28 18:54                   ` Steven Rostedt
2018-03-28 19:22                     ` Mathieu Desnoyers
2018-03-28 19:25                       ` Alexei Starovoitov
2018-03-28 19:32                       ` Steven Rostedt
2018-03-28 19:38                         ` Steven Rostedt [this message]
2018-03-28 19:47                           ` Mathieu Desnoyers
2018-03-28 17:14       ` Mathieu Desnoyers
2018-03-28  2:11 ` [PATCH v7 bpf-next 07/10] bpf: introduce BPF_RAW_TRACEPOINT Alexei Starovoitov
2018-03-28  2:11   ` Alexei Starovoitov
2018-03-28 17:41   ` Steven Rostedt
2018-03-28 17:41     ` Steven Rostedt
2018-03-28  2:11 ` [PATCH v7 bpf-next 08/10] libbpf: add bpf_raw_tracepoint_open helper Alexei Starovoitov
2018-03-28  2:11   ` Alexei Starovoitov
2018-03-28  2:11 ` [PATCH v7 bpf-next 09/10] samples/bpf: raw tracepoint test Alexei Starovoitov
2018-03-28  2:11   ` Alexei Starovoitov
2018-03-28  2:11 ` [PATCH v7 bpf-next 10/10] selftests/bpf: test for bpf_get_stackid() from raw tracepoints Alexei Starovoitov
2018-03-28  2:11   ` Alexei Starovoitov

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