From: Peter Zijlstra <peterz@infradead.org>
To: Jiri Olsa <jolsa@kernel.org>
Cc: Oleg Nesterov <oleg@redhat.com>,
Andrii Nakryiko <andrii@kernel.org>,
bpf@vger.kernel.org, Song Liu <songliubraving@fb.com>,
Yonghong Song <yhs@fb.com>,
John Fastabend <john.fastabend@gmail.com>,
Hao Luo <haoluo@google.com>, Steven Rostedt <rostedt@goodmis.org>,
Masami Hiramatsu <mhiramat@kernel.org>,
Alan Maguire <alan.maguire@oracle.com>,
linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org,
Will Deacon <will@kernel.org>,
Mark Rutland <mark.rutland@arm.com>
Subject: Re: [RFC 00/11] uprobes: Add support to optimize usdt probes on x86_64
Date: Sun, 17 Nov 2024 12:49:46 +0100 [thread overview]
Message-ID: <20241117114946.GD27667@noisy.programming.kicks-ass.net> (raw)
In-Reply-To: <20241105133405.2703607-1-jolsa@kernel.org>
On Tue, Nov 05, 2024 at 02:33:54PM +0100, Jiri Olsa wrote:
> hi,
> this patchset adds support to optimize usdt probes on top of 5-byte
> nop instruction.
>
> The generic approach (optimize all uprobes) is hard due to emulating
> possible multiple original instructions and its related issues. The
> usdt case, which stores 5-byte nop seems much easier, so starting
> with that.
>
> The basic idea is to replace breakpoint exception with syscall which
> is faster on x86_64. For more details please see changelog of patch 7.
So this is really about the fact that syscalls are faster than traps on
x86_64? Is there something similar on ARM64, or are they roughly the
same speed there?
That is, I don't think this scheme will work for the various RISC
architectures, given their very limited immediate range turns a typical
call into a multi-instruction trainwreck real quick.
Now, that isn't a problem if their exceptions and syscalls are of equal
speed.
next prev parent reply other threads:[~2024-11-17 11:49 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-11-05 13:33 [RFC 00/11] uprobes: Add support to optimize usdt probes on x86_64 Jiri Olsa
2024-11-05 13:33 ` [RFC perf/core 01/11] uprobes: Rename arch_uretprobe_trampoline function Jiri Olsa
2024-11-05 13:33 ` [RFC perf/core 02/11] uprobes: Make copy_from_page global Jiri Olsa
2024-11-14 23:40 ` Andrii Nakryiko
2024-11-16 21:41 ` Jiri Olsa
2024-11-05 13:33 ` [RFC perf/core 03/11] uprobes: Add len argument to uprobe_write_opcode Jiri Olsa
2024-11-14 23:41 ` Andrii Nakryiko
2024-11-16 21:41 ` Jiri Olsa
2024-11-05 13:33 ` [RFC perf/core 04/11] uprobes: Add data argument to uprobe_write_opcode function Jiri Olsa
2024-11-14 23:41 ` Andrii Nakryiko
2024-11-16 21:43 ` Jiri Olsa
2024-11-05 13:33 ` [RFC perf/core 05/11] uprobes: Add mapping for optimized uprobe trampolines Jiri Olsa
2024-11-05 14:23 ` Peter Zijlstra
2024-11-05 16:33 ` Jiri Olsa
2024-11-14 23:44 ` Andrii Nakryiko
2024-11-16 21:44 ` Jiri Olsa
2024-11-19 6:06 ` Andrii Nakryiko
2024-11-19 9:13 ` Peter Zijlstra
2024-11-19 15:15 ` Jiri Olsa
2024-11-21 0:07 ` Andrii Nakryiko
2024-11-21 11:53 ` Peter Zijlstra
2024-11-21 16:02 ` Alexei Starovoitov
2024-11-21 16:34 ` Peter Zijlstra
2024-11-21 16:47 ` Alexei Starovoitov
2024-11-21 19:38 ` Mark Rutland
2024-11-14 23:44 ` Andrii Nakryiko
2024-11-16 21:44 ` Jiri Olsa
2024-11-19 6:05 ` Andrii Nakryiko
2024-11-19 15:14 ` Jiri Olsa
2024-11-21 0:10 ` Andrii Nakryiko
2024-11-05 13:34 ` [RFC perf/core 06/11] uprobes: Add uprobe syscall to speed up uprobe Jiri Olsa
2024-11-05 13:34 ` [RFC perf/core 07/11] uprobes/x86: Add support to optimize uprobes Jiri Olsa
2024-11-14 23:44 ` Andrii Nakryiko
2024-11-16 21:44 ` Jiri Olsa
2024-11-18 8:18 ` Masami Hiramatsu
2024-11-18 9:39 ` Jiri Olsa
2024-11-05 13:34 ` [RFC bpf-next 08/11] selftests/bpf: Use 5-byte nop for x86 usdt probes Jiri Olsa
2024-11-05 13:34 ` [RFC bpf-next 09/11] selftests/bpf: Add usdt trigger bench Jiri Olsa
2024-11-14 23:40 ` Andrii Nakryiko
2024-11-16 21:45 ` Jiri Olsa
2024-11-19 6:08 ` Andrii Nakryiko
2024-11-05 13:34 ` [RFC bpf-next 10/11] selftests/bpf: Add uprobe/usdt optimized test Jiri Olsa
2024-11-05 13:34 ` [RFC bpf-next 11/11] selftests/bpf: Add hit/attach/detach race optimized uprobe test Jiri Olsa
2024-11-17 11:49 ` Peter Zijlstra [this message]
2024-11-18 9:29 ` [RFC 00/11] uprobes: Add support to optimize usdt probes on x86_64 Jiri Olsa
2024-11-18 10:06 ` Mark Rutland
2024-11-19 6:13 ` Andrii Nakryiko
2024-11-21 18:18 ` Mark Rutland
2024-11-26 19:13 ` Andrii Nakryiko
2024-11-18 8:04 ` Masami Hiramatsu
2024-11-18 9:52 ` Jiri Olsa
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