From nobody Wed Dec 17 16:01:16 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 0149D1607AB; Tue, 7 May 2024 14:15:09 +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=1715091310; cv=none; b=RM73hkEzDdejuQfn3JTRzRIeo6+HvQjasBC6W6+JykZ+z3UwKR7Ws/Rpmh/Rfdfc1hgb/uxUBTVShaCCFLlLy9GqTXID/OuHiFU7+1bTpJXkM10xVdPKN9Da6i0tVbqjMFnahImL8mkdGsvbh4SBbwy+WHJQlPzn901Ferc/KS4= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1715091310; c=relaxed/simple; bh=qz9bUI0E+avzydjRe5h6w3UDaf44DOCWwgWc2tfDYyI=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version:Content-Type; b=qrdUaF2yDjCVbb7nz3OfFK+voxljiDDf5IMTj1CDebn2pEzCg5EN6tjYT6WysT8YawFisoPhGVDF1XCmAd4aRco0/9e5R0eH/gbnRYmBwy7w3w4XFp2IFAnZ7QPMSa0tevigBsYjv/OxYtQYepRgxsNppDV97Ae8/sH8ayNNnHY= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=scBCwpI+; 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="scBCwpI+" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7EF06C2BBFC; Tue, 7 May 2024 14:15:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1715091309; bh=qz9bUI0E+avzydjRe5h6w3UDaf44DOCWwgWc2tfDYyI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=scBCwpI++kfSsaSK9E+iTNPa3Gn4Kpn7ej+TCsJq9/tvveZnHzDfK4ZdjVpc7TCbs npyUH8SXX+ysW7F18FoSNddiDpTlv86V9nOo+tD4UHZduDuX7vEut+K31++p/Ygi1U /ctNctmqffokczLd7vFi00arorqWT8QYVk/XWTHYe3wY0lAPtALVw6B6XQJvHFdkrJ ZUV4BMK25UOQ/EHs1wvjZ3oYdP52Cx5uxUYNN0z46rnVCVYsgYwGuSLPvlZ9cge6Cw YIsEs2ZSLiPqF0hIoJmgK07+3aaQH1eUK4jmGfJvgfjjYgOGN0bsNweRxA6vpzSI6t ByLq9Ng5RgvUw== 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 v10 36/36] fgraph: Skip recording calltime/rettime if it is not nneeded Date: Tue, 7 May 2024 23:15:02 +0900 Message-Id: <171509130284.162236.12400830886224359503.stgit@devnote2> X-Mailer: git-send-email 2.34.1 In-Reply-To: <171509088006.162236.7227326999861366050.stgit@devnote2> References: <171509088006.162236.7227326999861366050.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 v10: - Add likely() to skipping timestamp. Changes in v9: - Newly added. --- include/linux/ftrace.h | 2 ++ kernel/trace/fgraph.c | 51 +++++++++++++++++++++++++++++++++++++++++---= ---- kernel/trace/fprobe.c | 1 + 3 files changed, 47 insertions(+), 7 deletions(-) diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h index 64ca91d1527f..eb9de9d70829 100644 --- a/include/linux/ftrace.h +++ b/include/linux/ftrace.h @@ -1156,6 +1156,8 @@ struct fgraph_ops { struct ftrace_ops ops; /* for the hash lists */ void *private; 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 40f47fcbc6c3..13b41485ce49 100644 --- a/kernel/trace/fgraph.c +++ b/kernel/trace/fgraph.c @@ -138,6 +138,7 @@ DEFINE_STATIC_KEY_FALSE(kill_ftrace_graph); int ftrace_graph_active; =20 static struct fgraph_ops *fgraph_array[FGRAPH_ARRAY_SIZE]; +static bool fgraph_skip_timestamp; =20 /* LRU index table for fgraph_array */ static int fgraph_lru_table[FGRAPH_ARRAY_SIZE]; @@ -483,7 +484,7 @@ void ftrace_graph_stop(void) static int ftrace_push_return_trace(unsigned long ret, unsigned long func, unsigned long frame_pointer, unsigned long *retp, - int fgraph_idx) + int fgraph_idx, bool skip_ts) { struct ftrace_ret_stack *ret_stack; unsigned long long calltime; @@ -506,8 +507,12 @@ ftrace_push_return_trace(unsigned long ret, unsigned l= ong func, ret_stack =3D get_ret_stack(current, current->curr_ret_stack, &offset); if (ret_stack && ret_stack->func =3D=3D func && get_fgraph_type(current, offset + FGRAPH_FRAME_OFFSET) =3D=3D FGRAPH_= TYPE_BITMAP && - !is_fgraph_index_set(current, offset + FGRAPH_FRAME_OFFSET, fgraph_id= x)) + !is_fgraph_index_set(current, offset + FGRAPH_FRAME_OFFSET, fgraph_id= x)) { + /* If previous one skips calltime, update it. */ + if (!skip_ts && !ret_stack->calltime) + ret_stack->calltime =3D trace_clock_local(); return offset + FGRAPH_FRAME_OFFSET; + } =20 val =3D (FGRAPH_TYPE_RESERVED << FGRAPH_TYPE_SHIFT) | FGRAPH_FRAME_OFFSET; =20 @@ -525,7 +530,11 @@ 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(skip_ts)) + 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); @@ -609,7 +618,8 @@ int function_graph_enter_regs(unsigned long ret, unsign= ed long func, trace.func =3D func; trace.depth =3D ++current->curr_ret_depth; =20 - offset =3D ftrace_push_return_trace(ret, func, frame_pointer, retp, 0); + offset =3D ftrace_push_return_trace(ret, func, frame_pointer, retp, 0, + fgraph_skip_timestamp); if (offset < 0) goto out; =20 @@ -662,7 +672,8 @@ int function_graph_enter_ops(unsigned long ret, unsigne= d long func, return -ENODEV; =20 /* Use start for the distance to ret_stack (skipping over reserve) */ - offset =3D ftrace_push_return_trace(ret, func, frame_pointer, retp, gops-= >idx); + offset =3D ftrace_push_return_trace(ret, func, frame_pointer, retp, gops-= >idx, + gops->skip_timestamp); if (offset < 0) return offset; type =3D get_fgraph_type(current, offset); @@ -740,6 +751,7 @@ 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; + trace->rettime =3D 0; trace->overrun =3D atomic_read(¤t->trace_overrun); trace->depth =3D current->curr_ret_depth; /* @@ -800,7 +812,6 @@ __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 @@ -816,6 +827,12 @@ __ftrace_return_to_handler(struct ftrace_regs *fregs, = unsigned long frame_pointe continue; if (gops =3D=3D &fgraph_stub) continue; + /* + * This is not really 'unlikely' but for keeping the least path + * to be faster. + */ + if (unlikely(!trace.rettime && !gops->skip_timestamp)) + trace.rettime =3D trace_clock_local(); =20 gops->retfunc(&trace, gops, fregs); } @@ -1193,6 +1210,24 @@ static void init_task_vars(int idx) read_unlock(&tasklist_lock); } =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; @@ -1227,6 +1262,7 @@ 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 1) { register_pm_notifier(&ftrace_suspend_notifier); @@ -1250,6 +1286,7 @@ int register_ftrace_graph(struct fgraph_ops *gops) fgraph_array[i] =3D &fgraph_stub; ftrace_graph_active--; fgraph_lru_release_index(i); + update_fgraph_skip_timestamp(); } out: mutex_unlock(&ftrace_lock); @@ -1273,8 +1310,8 @@ 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;