From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) (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 3C9C72DF134; Fri, 9 Jan 2026 19:19:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=216.40.44.17 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767986345; cv=none; b=a3/UduMsWc6UaIOF7538XNuZNlrOrTq7Ui5sqD7YgkZxpQwWu+rmENgJHeIgxrHOW+xuQPHaqCsGGoSoJLiYFgMwlCwZRP6GKf2+034zYHb2adJhH/QSma26+k6sZ8bCHCNmCaif/UlvKzBIRxGk47ejgEuWMeIQOt9eVRJ90oY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767986345; c=relaxed/simple; bh=b9fkAHjAXiET4tDCdZO1d2UxiZ7wSIMCge1r9CaDPe4=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=me3nG2G6RLAoF7zG0gkhQMBCP8t47Krr/ho8n2gt6btR8PxYBH7Agrq/LEvJW2x5zKeXfP4kWUjuiU833TU0QNiNPOi6IHzkLIJ4ev2OVQalIgIp1Z9F4cAVrbH2AkECsJmaLR+W/1GF35g5CrWaM0kT5j0LWR628+sjMI2hhBU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=goodmis.org; spf=pass smtp.mailfrom=goodmis.org; arc=none smtp.client-ip=216.40.44.17 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=goodmis.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=goodmis.org Received: from omf10.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay03.hostedemail.com (Postfix) with ESMTP id AB4C6BB599; Fri, 9 Jan 2026 19:19:00 +0000 (UTC) Received: from [HIDDEN] (Authenticated sender: rostedt@goodmis.org) by omf10.hostedemail.com (Postfix) with ESMTPA id 80D2D3D; Fri, 9 Jan 2026 19:18:58 +0000 (UTC) Date: Fri, 9 Jan 2026 14:19:30 -0500 From: Steven Rostedt To: Alexei Starovoitov Cc: Mathieu Desnoyers , LKML , Linux trace kernel , bpf , Masami Hiramatsu , "Paul E. McKenney" , Sebastian Andrzej Siewior , Thomas Gleixner Subject: Re: [PATCH v5] tracing: Guard __DECLARE_TRACE() use of __DO_TRACE_CALL() with SRCU-fast Message-ID: <20260109141930.6deb2a0a@gandalf.local.home> In-Reply-To: References: <20260108220550.2f6638f3@fedora> X-Mailer: Claws Mail 3.20.0git84 (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 X-Rspamd-Queue-Id: 80D2D3D X-Stat-Signature: mrxwuctbtb6qzwocxk1ia8h7ctoxwbwk X-Rspamd-Server: rspamout08 X-Session-Marker: 726F737465647440676F6F646D69732E6F7267 X-Session-ID: U2FsdGVkX18cMV76IqjIgBX803+m9q4qinkTmK1Zris= X-HE-Tag: 1767986338-843608 X-HE-Meta: U2FsdGVkX19BAUi14sanQ9ajQTBpJxaO+v588L2XOniSoSYcGLFgUKxufpmR0en9l5+F99W2EiFzznSLDbaDocOPmF0Q0H5Cmgk1ZqzjH8A3Q3hnd/gBfpW75VfzYTdmuD+DZsKUzDf2u8vsk4tLcTdfYcQBv38ksntwQZmGwIKfYWBOqO457LbD1CTyLNI5pMUlmpbrhUGU1Lj5fhylOSkHt9DYm3RzcIX05uXPbkMGXxexc+CW8ocxjwP8TQP5vF+YhrNI+fteOITUftA0lvVUb1NGtmB3RbLKAEvGFn3BDIslz6sbJQ+X93S1tNUq5tTw584x0aSy1EaVpoZylQV94mVYcZnd On Fri, 9 Jan 2026 11:10:16 -0800 Alexei Starovoitov wrote: \> > > > 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. No need to make comments like that. The Linux kernel is an ocean of code. It's very hard to keep up on everything that is happening. I knew of work being done on migrate_disable but I didn't know what the impacts of that work was. Mathieu is still very much involved and engaged 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. It would be good to have a benchmark of the two. What about fast_srcu? Is that fast enough to replace the preempt_disable()? If so, then could we just make this the same for both RT and !RT? -- Steve