From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-189.mta0.migadu.com (out-189.mta0.migadu.com [91.218.175.189]) (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 ABFFB2DF134 for ; Fri, 9 Jan 2026 19:20:02 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.189 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767986404; cv=none; b=IyuShCP3PZFo0XV/tCTX4t03W7uw0EUFtP1q3MQKyqpeIS0s54bEYB2NoYGEg2RH0J3sqm396wGw3LoGgU2NXP2UxMiYcR6c6NAd4kGzcOblXA4f4iNaXTmqRfZili2sJME8k4snkxcwWVo9nf+QafqKHSJ3HRO3v0ttEECxNMA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767986404; c=relaxed/simple; bh=UA1W3ffSHy7mmLgxQmLPlqFxO0jlzVXsdLrfVgn9j0g=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=k7Whj45uA+V8hNUuhpS0RTf0CmtnmCjjMZauWgEKsfItR2pBdM376vGt7YdryQjssLLxGh8i9Qi9P11dvJn3mch0sh5xc9w7np5xMozOcxsmuR8+bBitDjJBRqA3l0bc5bTV/VG+5mbymH2mVSg3S6ygCygdJ9XU0tEHNflNvmg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=Vttmsl0D; arc=none smtp.client-ip=91.218.175.189 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="Vttmsl0D" Message-ID: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1767986400; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=UA1W3ffSHy7mmLgxQmLPlqFxO0jlzVXsdLrfVgn9j0g=; b=Vttmsl0DV1JUxe2J1IX2yXZn0oMFTmNsr0ZW1XJKtM/WQGp/gwI+E52GE0zK5yP6JfadOM sw78Cdxe3/6bazMgiHftgF8t4uwBnxNmPRqjgnbQruZ+KbB9q9RTy5SHTkrQiLNTB1l4gF wklC42gZp+4Ln5jS2V7V6iCt5ZfdwF0= Date: Fri, 9 Jan 2026 11:19:55 -0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Subject: Re: [PATCH v5] tracing: Guard __DECLARE_TRACE() use of __DO_TRACE_CALL() with SRCU-fast Content-Language: en-GB To: Alexei Starovoitov , Mathieu Desnoyers Cc: Steven Rostedt , LKML , Linux trace kernel , bpf , Masami Hiramatsu , "Paul E. McKenney" , Sebastian Andrzej Siewior , Thomas Gleixner References: <20260108220550.2f6638f3@fedora> X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Yonghong Song In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT On 1/9/26 11:10 AM, Alexei Starovoitov wrote: > On Fri, Jan 9, 2026 at 6:45 AM Mathieu Desnoyers > wrote: >> On 2026-01-08 22:05, Steven Rostedt wrote: >>> From: "Paul E. McKenney" >> [...] >> >> I disagree with many elements of the proposed approach. >> >> On one end we have BPF wanting to hook on arbitrary tracepoints without >> adding significant latency to PREEMPT RT kernels. >> >> One the other hand, we have high-speed tracers which execute very short >> critical sections to serialize trace data into ring buffers. >> >> All of those users register to the tracepoint API. >> >> We also have to consider that migrate disable is *not* cheap at all >> compared to preempt disable. > Looks like your complaint comes from lack of engagement in kernel > development. > migrate_disable _was_ not cheap. > Try to benchmark it now. > It's inlined. It's a fraction of extra overhead on top of preempt_disable. > The following are related patches to inline migrate_disable(): 35561bab768977c9e05f1f1a9bc00134c85f3e28 arch: Add the macro COMPILE_OFFSETS to all the asm-offsets.c 88a90315a99a9120cd471bf681515cc77cd7cdb8 rcu: Replace preempt.h with sched.h in include/linux/rcupdate.h 378b7708194fff77c9020392067329931c3fcc04 sched: Make migrate_{en,dis}able() inline