From mboxrd@z Thu Jan 1 00:00:00 1970 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 B4A6EA955; Fri, 4 Oct 2024 00:17:31 +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=1728001051; cv=none; b=CpeUPamGCnMaVD+YRb+xAyoqlKXIvYKScIFsEsjs6cZT4rBSdVkk0eSzTpF03Y6aDOe8iv/MtaZJg/pVe9q2b57VckRbvq2QaLYmu77eQg12nNEGagqF2+L5+AhG4GgtFtGFukU/T2UA6YL7YDuZCQ+8qzDn0LhR860bvh54/OI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728001051; c=relaxed/simple; bh=uAQH/D0FoMoHKemDrU0RQ8iSL3VlPrfdWfV8B4knhOI=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=WnPIsbQrfa9tlejWRpEA2H4SREGgUnnXlbJCFndknzgXvHSyGC9NFxTYmqJ4VWfehbOcOB4zZnoCNNx9phgNJMx8j15CjSshBym8kqoNRAxInKTOdKmXNINdPvBGAfrPy+ywRHYPC3gLE4HHzi9cuKr8mcmb9gLjKvcNR5wWukw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=brQBChuy; 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="brQBChuy" Received: by smtp.kernel.org (Postfix) with ESMTPSA id EC767C4CEC7; Fri, 4 Oct 2024 00:17:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1728001051; bh=uAQH/D0FoMoHKemDrU0RQ8iSL3VlPrfdWfV8B4knhOI=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=brQBChuyDFc3VHRJwHwg2QNSsol7E9ZDmiPX7KKc0uuT1H7XjaCbe2kMw16BqLJNK dLll9aqx5H+RxbCr/b00H6zSoo7+H0e0bsHq0BqzClEZ4iNROycpOSRnNaOxTedlsF Xxxrzx6r1CdjoGTHwvtjPFUjFx6X2bZvKdeg9q8V/ZY3vCIYC24GN16BKs1FLzUbPx q2KrQAzQEEdpEeSGHuA6nFKDl2bAHhox8bw4Cv7X+gpdjz8eQey9DA1WwxRnFRQ5vm pjcpFLHD/34X8G8FJKzBi7XNyhaI/+7hrtz6hiUnaZrGdfdHovpjka/55UyXwCqVmh P+6f9JkJGdFRg== Date: Fri, 4 Oct 2024 02:17:28 +0200 From: Frederic Weisbecker To: Steven Rostedt Cc: Mathieu Desnoyers , Masami Hiramatsu , linux-kernel@vger.kernel.org, Peter Zijlstra , Alexei Starovoitov , Yonghong Song , "Paul E . McKenney" , Ingo Molnar , Arnaldo Carvalho de Melo , Mark Rutland , Alexander Shishkin , Namhyung Kim , Andrii Nakryiko , bpf@vger.kernel.org, Joel Fernandes , linux-trace-kernel@vger.kernel.org, Michael Jeanson , Frederic Weisbecker Subject: Re: [PATCH v1 3/8] tracing/perf: guard syscall probe with preempt_notrace Message-ID: References: <20241003151638.1608537-1-mathieu.desnoyers@efficios.com> <20241003151638.1608537-4-mathieu.desnoyers@efficios.com> <20241003182508.6ca76abc@gandalf.local.home> 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=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20241003182508.6ca76abc@gandalf.local.home> Le Thu, Oct 03, 2024 at 06:25:08PM -0400, Steven Rostedt a écrit : > On Thu, 3 Oct 2024 11:16:33 -0400 > Mathieu Desnoyers wrote: > > > In preparation for allowing system call enter/exit instrumentation to > > handle page faults, make sure that perf can handle this change by > > explicitly disabling preemption within the perf system call tracepoint > > probes to respect the current expectations within perf ring buffer code. > > > > This change does not yet allow perf to take page faults per se within > > its probe, but allows its existing probes to adapt to the upcoming > > change. > > Frederic, > > Does the perf ring buffer expect preemption to be disabled when used? > > In other words, is this patch needed? At least the trace events perf callback requires that because it uses a per cpu buffer (see perf_trace_buf_alloc()). Thanks.