From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 21B94161; Mon, 27 May 2024 00:04:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1716768281; cv=none; b=JfLnv9pDaaC8echBKxcBAJyCvFJ2co7lXgXIt9LjNI48OPzLwzloV08Cb4k5QdteQdMSz24+QzQa/IM74XqHSN7iSS9rK/92cLSd23QmXj1Pmp7F30OWZKECR5HsFSk2UUF4iJUBkFPH6fkxXkI4t7suEtJD6h5hz31jAyOpIow= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1716768281; c=relaxed/simple; bh=PcmYPBGo2XhGqyaercyt+IZ2k2DlEHd7kUXcc3kQ2Eg=; h=Date:From:To:Cc:Subject:Message-Id:In-Reply-To:References: Mime-Version:Content-Type; b=Na0WHFF7aW9Q4nVEU4fthGx/N5WKgbf2qLTvr8BZCTbUR4ZYBKK94wZofRm/DiaA9bXZKjLdG16kmIZLs8xIXMcjuP+QCUB0uAbdtHNzGS1d2Vc1E/GnmjNg2HMbSuYEMlujl7muZ0Y3tNmqJs8IIqysy89qJzoA1yc436U3Npw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=XPHIv4TU; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="XPHIv4TU" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A68FBC2BD10; Mon, 27 May 2024 00:04:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1716768280; bh=PcmYPBGo2XhGqyaercyt+IZ2k2DlEHd7kUXcc3kQ2Eg=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=XPHIv4TUHywo6ZiY57edG8kmeD1+Rq26K8hDgEJMBVnMLGbM9vHo1Oy8CL+dTsGpY mQi3lpj9L/726bC4JQz4oY48jQrnT+iM0YOR/2HpzfJd7W6XAaGEGAiMXMACo67O+L GNzm3KMhZzmiWDLJNW5Gg0I8O0kjMSIdE0VNnU03cxndP5IqGF+0tc54/lM5e+q910 pVM/rise3d+5ZJpDNoYYZZiLQrL1UorcdoXt7grS4Mb/kRLrNxWYlnBrOsT9J533qJ nTcaXRdGOy0UE84Xl/Kmq29Vp5v+Ohkq4WG8rJJwouDUZh5CeloxpfkGyYb6ekbATa M20Pi0Yu92zfw== Date: Mon, 27 May 2024 09:04:34 +0900 From: Masami Hiramatsu (Google) To: Steven Rostedt Cc: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, Masami Hiramatsu , Mark Rutland , Mathieu Desnoyers , Andrew Morton , Alexei Starovoitov , Florent Revest , Martin KaFai Lau , bpf , Sven Schnelle , Alexei Starovoitov , Jiri Olsa , Arnaldo Carvalho de Melo , Daniel Borkmann , Alan Maguire , Peter Zijlstra , Thomas Gleixner , Guo Ren Subject: Re: [PATCH 19/20] function_graph: Use for_each_set_bit() in __ftrace_return_to_handler() Message-Id: <20240527090434.37e309d0280d6d8f116edc85@kernel.org> In-Reply-To: <20240525023744.231570357@goodmis.org> References: <20240525023652.903909489@goodmis.org> <20240525023744.231570357@goodmis.org> X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Fri, 24 May 2024 22:37:11 -0400 Steven Rostedt wrote: > From: "Steven Rostedt (Google)" > > Instead of iterating through the entire fgraph_array[] and seeing if one > of the bitmap bits are set to know to call the array's retfunc() function, > use for_each_set_bit() on the bitmap itself. This will only iterate for > the number of set bits. > > Signed-off-by: Steven Rostedt (Google) > --- > kernel/trace/fgraph.c | 5 ++--- > 1 file changed, 2 insertions(+), 3 deletions(-) > > diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c > index 4d503b3e45ad..5e8e13ffcfb6 100644 > --- a/kernel/trace/fgraph.c > +++ b/kernel/trace/fgraph.c > @@ -827,11 +827,10 @@ static unsigned long __ftrace_return_to_handler(struct fgraph_ret_regs *ret_regs > #endif > > bitmap = get_bitmap_bits(current, offset); > - for (i = 0; i < FGRAPH_ARRAY_SIZE; i++) { > + > + for_each_set_bit(i, &bitmap, sizeof(bitmap) * BITS_PER_BYTE) { > struct fgraph_ops *gops = fgraph_array[i]; > > - if (!(bitmap & BIT(i))) > - continue; > if (gops == &fgraph_stub) Ah, nit: maybe this is unlikely()? Thank you, -- Masami Hiramatsu (Google)