From nobody Thu Dec 18 10:35:26 2025 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 28B8212FF6A; Mon, 17 Jun 2024 01:50:02 +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=1718589003; cv=none; b=goj5RzJT+uNtZMLdDhcITQDJld6uI7M8wTUhRLKcEBphz2p0knQ4Ca5n2MDiJZA3EnS+dQau9S2iE3OEDHLs5a0BsghXn7lZWIMgGfFq20l3AET3sPUFC5BmP3fqutCfNRea23XSq3UqYTPBTkMXoTv0utNcusagc8JGimH8PeU= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718589003; c=relaxed/simple; bh=NheZlQukXrHe+aAqSQt20W9ihRV2X4255gLoqcg7brw=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version:Content-Type; b=CpRSLUcuZ8bCIMQXpV9cZopsvm9ean1BFHDzfkRwg7yO2qSe550XnWYgvtyWb/o2NnVrOCA5x0PIuIMkk5WHDjJLIELhIU0MR8+tufcyuWM48+Qx4F8RKf0T2RlQN1XZ4sJyCN4syfpLeMXN3Y6hvmAoiHA1P/CR44rLO39RRVU= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=nw6QVtQR; 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="nw6QVtQR" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E9BF3C2BBFC; Mon, 17 Jun 2024 01:49:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1718589002; bh=NheZlQukXrHe+aAqSQt20W9ihRV2X4255gLoqcg7brw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=nw6QVtQRaoS4WUF3g1P6l1m+RA1PnZV72WOfiuhHMQp2RepZEjWMZ+p+eLz3++27w wp8bfJ4EYJ7in0idip8Tj0CEV9qQQUwogJV7/T6iPOji2mfuLz2CW93nEojZU0B0OJ JCkzRoSzxyVPinmUibxs3zSKwj+ws10ssP3n0YxfG6bZ+HIqkn9MTBrX5H9+NVR6mz 1lzMfJAwoufluGbRrI0tYSOMO5mwR/sirD7eTz+m65rZD8nEudr9pBAOEp6l6UyOV7 SS1fAcSvHirzNREvkPr2e8rXB8uaGhn1Ae/nZVHrHDsSBSuCTwJN93DxMd1t/vn9kK BcVx7Bnwhq5uA== From: "Masami Hiramatsu (Google)" To: Alexei Starovoitov , Steven Rostedt , Florent Revest Cc: linux-trace-kernel@vger.kernel.org, LKML , Martin KaFai Lau , bpf , Sven Schnelle , Alexei Starovoitov , Jiri Olsa , Arnaldo Carvalho de Melo , Daniel Borkmann , Alan Maguire , Mark Rutland , Peter Zijlstra , Thomas Gleixner , Guo Ren Subject: [PATCH v11 18/18] fgraph: Skip recording calltime/rettime if it is not nneeded Date: Mon, 17 Jun 2024 10:49:56 +0900 Message-Id: <171858899671.288820.1294786279157013093.stgit@devnote2> X-Mailer: git-send-email 2.34.1 In-Reply-To: <171858878797.288820.237119113242007537.stgit@devnote2> References: <171858878797.288820.237119113242007537.stgit@devnote2> User-Agent: StGit/0.19 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable From: Masami Hiramatsu (Google) Skip recording calltime and rettime if the fgraph_ops does not need it. This is a kind of performance optimization for fprobe. Since the fprobe user does not use these entries, recording timestamp in fgraph is just a overhead (e.g. eBPF, ftrace). So introduce the skip_timestamp flag, and all fgraph_ops sets this flag, skip recording calltime and rettime. Suggested-by: Jiri Olsa Signed-off-by: Masami Hiramatsu (Google) --- Changes in v11: - Simplify it to be symmetric on push and pop. (Thus the timestamp getting place is a bit shifted.) Changes in v10: - Add likely() to skipping timestamp. Changes in v9: - Newly added. --- include/linux/ftrace.h | 2 ++ kernel/trace/fgraph.c | 36 +++++++++++++++++++++++++++++++++--- kernel/trace/fprobe.c | 1 + 3 files changed, 36 insertions(+), 3 deletions(-) diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h index d8a58b940d81..fabf1a0979d4 100644 --- a/include/linux/ftrace.h +++ b/include/linux/ftrace.h @@ -1160,6 +1160,8 @@ struct fgraph_ops { void *private; trace_func_graph_ent_t saved_func; int idx; + /* If skip_timestamp is true, this does not record timestamps. */ + bool skip_timestamp; }; =20 void *fgraph_reserve_data(int idx, int size_bytes); diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c index d735a8c872bb..cf3ae59a436e 100644 --- a/kernel/trace/fgraph.c +++ b/kernel/trace/fgraph.c @@ -174,6 +174,7 @@ int ftrace_graph_active; =20 static struct fgraph_ops *fgraph_array[FGRAPH_ARRAY_SIZE]; static unsigned long fgraph_array_bitmask; +static bool fgraph_skip_timestamp; =20 /* LRU index table for fgraph_array */ static int fgraph_lru_table[FGRAPH_ARRAY_SIZE]; @@ -557,7 +558,11 @@ ftrace_push_return_trace(unsigned long ret, unsigned l= ong func, return -EBUSY; } =20 - calltime =3D trace_clock_local(); + /* This is not really 'likely' but for keeping the least path to be faste= r. */ + if (likely(fgraph_skip_timestamp)) + calltime =3D 0LL; + else + calltime =3D trace_clock_local(); =20 offset =3D READ_ONCE(current->curr_ret_stack); ret_stack =3D RET_STACK(current, offset); @@ -728,6 +733,12 @@ ftrace_pop_return_trace(struct ftrace_graph_ret *trace= , unsigned long *ret, *ret =3D ret_stack->ret; trace->func =3D ret_stack->func; trace->calltime =3D ret_stack->calltime; + /* This is not really 'likely' but for keeping the least path to be faste= r. */ + if (likely(!trace->calltime)) + trace->rettime =3D 0LL; + else + trace->rettime =3D trace_clock_local(); + trace->overrun =3D atomic_read(¤t->trace_overrun); trace->depth =3D current->curr_ret_depth; /* @@ -788,7 +799,6 @@ __ftrace_return_to_handler(struct ftrace_regs *fregs, u= nsigned long frame_pointe return (unsigned long)panic; } =20 - trace.rettime =3D trace_clock_local(); if (fregs) ftrace_regs_set_instruction_pointer(fregs, ret); =20 @@ -1242,6 +1252,24 @@ static void ftrace_graph_disable_direct(bool disable= _branch) fgraph_direct_gops =3D &fgraph_stub; } =20 +static void update_fgraph_skip_timestamp(void) +{ + int i; + + for (i =3D 0; i < FGRAPH_ARRAY_SIZE; i++) { + struct fgraph_ops *gops =3D fgraph_array[i]; + + if (gops =3D=3D &fgraph_stub) + continue; + + if (!gops->skip_timestamp) { + fgraph_skip_timestamp =3D false; + return; + } + } + fgraph_skip_timestamp =3D true; +} + int register_ftrace_graph(struct fgraph_ops *gops) { int command =3D 0; @@ -1267,6 +1295,7 @@ int register_ftrace_graph(struct fgraph_ops *gops) gops->idx =3D i; =20 ftrace_graph_active++; + update_fgraph_skip_timestamp(); =20 if (ftrace_graph_active =3D=3D 2) ftrace_graph_disable_direct(true); @@ -1298,6 +1327,7 @@ int register_ftrace_graph(struct fgraph_ops *gops) ftrace_graph_active--; gops->saved_func =3D NULL; fgraph_lru_release_index(i); + update_fgraph_skip_timestamp(); } out: mutex_unlock(&ftrace_lock); @@ -1321,8 +1351,8 @@ void unregister_ftrace_graph(struct fgraph_ops *gops) goto out; =20 fgraph_array[gops->idx] =3D &fgraph_stub; - ftrace_graph_active--; + update_fgraph_skip_timestamp(); =20 if (!ftrace_graph_active) command =3D FTRACE_STOP_FUNC_RET; diff --git a/kernel/trace/fprobe.c b/kernel/trace/fprobe.c index afa52d9816cf..24bb8edec8a3 100644 --- a/kernel/trace/fprobe.c +++ b/kernel/trace/fprobe.c @@ -345,6 +345,7 @@ NOKPROBE_SYMBOL(fprobe_return); static struct fgraph_ops fprobe_graph_ops =3D { .entryfunc =3D fprobe_entry, .retfunc =3D fprobe_return, + .skip_timestamp =3D true, }; static int fprobe_graph_active;