From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) (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 A8DFB3612CB; Mon, 12 Jan 2026 15:36:13 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=216.40.44.16 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768232175; cv=none; b=FxyaSN4+MCPTitQ6cil7Sw4036tVBgY+DLZBjTInikkxRw2h/DYrbbKng8PsufaCUY7cigpnaO/1Gaq+vd6QUET/L6cFDTVb02fUKpQPh1LY6yQKwfq1YiG+dteDx9NEbf5K6UtfzrMv8kVS5ldtFHjPJzWtgfHPdJLeQbGoqSg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768232175; c=relaxed/simple; bh=IJTeafi3GdmngR/Ug8cbCa4yRhJh7eOjuoI6sV6L7u8=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=fFnp3u2sJ/4K+Khi5DqC+fL6YwVSxTz3QCE6UwyVMYJ894epZL9aZrlkwKvaKCI7eKXSnsWgO9pQmXotgg7ny9aLnxJYm5t2s6r9Kk0Q3RGchoAVKke/rDifKeNUMNPIjhV7VCmUazN8mDuloIvWGW2HI/Jbgff6Xx0dGsNYkwg= 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=216.40.44.16 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 omf01.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay01.hostedemail.com (Postfix) with ESMTP id C5417D0F22; Mon, 12 Jan 2026 15:36:11 +0000 (UTC) Received: from [HIDDEN] (Authenticated sender: rostedt@goodmis.org) by omf01.hostedemail.com (Postfix) with ESMTPA id 78FE060009; Mon, 12 Jan 2026 15:36:09 +0000 (UTC) Date: Mon, 12 Jan 2026 10:36:12 -0500 From: Steven Rostedt To: Peter Zijlstra Cc: Mathieu Desnoyers , Alexei Starovoitov , LKML , Linux trace kernel , bpf , Masami Hiramatsu , "Paul E. McKenney" , Sebastian Andrzej Siewior , Thomas Gleixner , Linus Torvalds Subject: Re: [PATCH v5] tracing: Guard __DECLARE_TRACE() use of __DO_TRACE_CALL() with SRCU-fast Message-ID: <20260112103612.41dd4f03@gandalf.local.home> In-Reply-To: <20260112153128.GO830755@noisy.programming.kicks-ass.net> References: <20260108220550.2f6638f3@fedora> <20260109141930.6deb2a0a@gandalf.local.home> <3c0df437-f6e5-47c6-aed5-f4cc26fe627a@efficios.com> <20260109160202.22975aa4@gandalf.local.home> <20260112153128.GO830755@noisy.programming.kicks-ass.net> 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: 78FE060009 X-Stat-Signature: 1bw1oymr1hzm7aif4p945ohzhcf8qy8i X-Rspamd-Server: rspamout05 X-Session-Marker: 726F737465647440676F6F646D69732E6F7267 X-Session-ID: U2FsdGVkX188wDl0ClLWtdgAsR3BixK7EB7H0d78LlA= X-HE-Tag: 1768232169-489420 X-HE-Meta: U2FsdGVkX1+25cV6CkjInKsAbuf455j8HF4zIIWJCb05b5Z+ZtTTGVIxEHyWOaEHHSdnB9fsl8qRwU2XZCu9j/3UtsvVRiB1HdKMXSTL6+J92LberiGxt34Y6/c4teMSnU5PZ745Zq1u1LkJLtQvnCERC3AXPDzgYDBRJUdDR6Fc43RvOudT0uZgp/tXcQeyJC5lGXX5cpTsEEK5t85cLPSUYb5Xd/US8CKkiomGTe7stWFD+8P7b70WrtJIeWMgC+uFmyFdncl082dPu1/mUKoh1F5qqVxCNj8CUF9R64FZ3JxMBczoQ4T83HJBccWgBWZOrbr+GAX0SzH3bKO6FBhK9Gsw1vdRKs1Kk7xvcZwzLgVMhvcmsjmJYCWliZC9 On Mon, 12 Jan 2026 16:31:28 +0100 Peter Zijlstra wrote: > > OUCH! So migrate disable/enable has a much larger overhead when executed in > > a module than in the kernel? This means all spin_locks() in modules > > converted to mutexes in PREEMPT_RT are taking this hit! > > Not so, the migrate_disable() for PREEMPT_RT is still in core code -- > kernel/locking/spinlock_rt.c is very much not build as a module. True. But still, wouldn't it be cleaner to have that variable separate from the run queue and make the code a bit simpler? As now it doesn't look like it will even bother tracing, as it appears that only BPF would need it. So this would just be a clean up. -- Steve