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From: Jiri Olsa <olsajiri@gmail.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>,
	Naveen N Rao <naveen@kernel.org>,
	"David S. Miller" <davem@davemloft.net>,
	Josh Poimboeuf <jpoimboe@kernel.org>,
	Jason Baron <jbaron@akamai.com>,
	Alice Ryhl <aliceryhl@google.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Ard Biesheuvel <ardb@kernel.org>,
	Thomas Gleixner <tglx@kernel.org>, Ingo Molnar <mingo@redhat.com>,
	Alan Maguire <almagui@kernel.org>,
	x86@kernel.org, linux-trace-kernel@vger.kernel.org,
	linux-kernel@vger.kernel.org, bpf@vger.kernel.org
Subject: Re: [PATCH 01/13] static_call: Index code text reservation lookups
Date: Thu, 12 Nov 2026 19:33:03 +0100	[thread overview]
Message-ID: <avYGX1UpGlvbvHO5@krava> (raw)
In-Reply-To: <20261112101108.GE2669272@noisy.programming.kicks-ass.net>

On Thu, Nov 12, 2026 at 11:11:08AM +0100, Peter Zijlstra wrote:
> On Thu, Nov 12, 2026 at 10:07:34AM +0100, Peter Zijlstra wrote:
> > Looking at this in a little more detail; I'm confused. 
> > 
> > You're literally adding an index, so that you can find the
> > static_call_size, while all you really need is static_call_addr().
> 
> /size/site/ obviously :-)
> 
> > That is, you could have just created an array of relocated site->addr
> > and sorted that, that would safe you a ton of indirection all around.
> > 
> > That is:
> > 
> > 	index->entries[i] = (long)static_call_addr(start + i) - (long)&index->entries[i];
> 
> Should be:
> 
>  	index->entries[i] = (long)static_call_addr(start + i) - (long)index->entries;
> 
> They have to all be relative to one location in order for sorting to
> make sense.
> 
> > That will make your lookup take at least half the amount of loads.

hum, but we still need the site’s init flag for static_call_is_init

I could store site pointer directly instead of the index and see how
much faster it is


> > 
> > 
> > Also, you really should support modules, there is no point being fast
> > until you load a module.

I had that, but decided to remove it because my follow up changes
did not support modules as well.. I will include it

jirka

  reply	other threads:[~2026-11-12 18:33 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-11-09 19:49 [PATCH 00/13] kprobes: Reduce registration and optimization lookup costs Jiri Olsa
2026-11-09 19:49 ` [PATCH 01/13] static_call: Index code text reservation lookups Jiri Olsa
2026-11-12  8:27   ` Peter Zijlstra
2026-11-12 18:33     ` Jiri Olsa
2026-11-12  8:34   ` Peter Zijlstra
2026-11-12 18:33     ` Jiri Olsa
2026-11-12  9:07   ` Peter Zijlstra
2026-11-12 10:11     ` Peter Zijlstra
2026-11-12 18:33       ` Jiri Olsa [this message]
2026-11-09 19:49 ` [PATCH 02/13] jump_label: Index " Jiri Olsa
2026-11-12  8:33   ` Peter Zijlstra
2026-11-12 18:33     ` Jiri Olsa
2026-11-09 19:49 ` [PATCH 03/13] jump_label/x86: Avoid decoding instructions for jump entry size Jiri Olsa
2026-11-12  8:39   ` Peter Zijlstra
2026-11-12 18:33     ` Jiri Olsa
2026-11-09 19:55 ` [PATCH 04/13] kprobes: Maintain an rbtree of registered probes Jiri Olsa
2026-11-10  8:12   ` Masami Hiramatsu (Google)
2026-11-10 10:37     ` Jiri Olsa
2026-11-10 15:38       ` Masami Hiramatsu (Google)
2026-11-11 10:49         ` Jiri Olsa
2026-11-10 23:45   ` sashiko-bot
2026-11-12  8:50   ` Peter Zijlstra
2026-11-09 19:56 ` [PATCH 05/13] kprobes: Add an iterator for address ranges Jiri Olsa
2026-11-09 19:56 ` [PATCH 06/13] kprobes: Add an address iterator for probe lookup Jiri Olsa
2026-11-09 19:56 ` [PATCH 07/13] kprobes: Use kprobe iterator in get_optimized_kprobe Jiri Olsa
2026-11-09 19:57 ` [PATCH 08/13] x86/kprobes: Use kprobe iterator in __recover_optprobed_insn Jiri Olsa
2026-11-09 19:57 ` [PATCH 09/13] x86/kprobes: Use kprobe iterator in arch_check_optimized_kprobe Jiri Olsa
2026-11-11  0:17   ` sashiko-bot
2026-11-09 19:57 ` [PATCH 10/13] x86/kprobes: Use kprobe address iterator in can_optimize Jiri Olsa
2026-11-09 19:57 ` [PATCH 11/13] x86/kprobes: Use kprobe address iterator in can_probe Jiri Olsa
2026-11-09 19:58 ` [PATCH 12/13] x86/kprobes: Use kprobe address iterator in in copy_optimized_instructions Jiri Olsa
2026-11-09 19:58 ` [PATCH 13/13] samples/kprobes: Add batch probe example Jiri Olsa
2026-11-11  0:49   ` sashiko-bot
2026-11-11  2:20   ` kernel test robot

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