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 5A3441684A4; Sun, 4 May 2025 09:42:00 +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=1746351721; cv=none; b=oz5F+MMw2MpqhjL5wIsK+6LJH+mvGHM3B0X9Uf2DGy+ecChzus3c0NWuS3D0VcGBzP/mwVLGS6RJH+z8yReL9p+ygTmpcncklafRAuvfejwaWmszGKw1UYiUnlgKkGzMy66xxSOMCvpJewQa6Gq56pmR1KCBu1dGp+lucBW4Qk0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1746351721; c=relaxed/simple; bh=dSzA91nB8CHSr5Hse/nAOssPhfcOywqtv0vsP7ZdSZk=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=oNy7LKpygDDovSSdTIFTKSLVj39oUPxuoouGGQjC6dEHzS2wykBtlSfooLnWGVHu4gJnGV2buYJH44lHGgnHZ4U9a4NoB57y8ICSYlkIMI4MRK2M/gHr0bnV5bWGZEq6RGmJ/RZNe/IrAdI3JLYFZLJFC8rgIcVDhNtAWRPTcCk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=D6kiUgse; 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="D6kiUgse" Received: by smtp.kernel.org (Postfix) with ESMTPSA id F0802C4CEE7; Sun, 4 May 2025 09:41:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1746351720; bh=dSzA91nB8CHSr5Hse/nAOssPhfcOywqtv0vsP7ZdSZk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=D6kiUgseaMvEWkO9T1um+E/WfyFjnTdfWEdsxtmEjGz8YsP7CQ0P51slYCCfcVyl5 IBijlAyqvCQpp4R7rxgUEJ+dr4v+z1BcFj5viKEJxR+hbb1+CgXYn7gCk2m75htSli h77ZFZbbcig0MHHYaYDXHp8mgbkvLA5AcQmZz02Pk195YhSd+GuE2w5l5BtiD4PMUN W9NzADD5zwAUR7kehlMiO2dtQd9dcvu3qgfVs+sfUj9byKVj4wfx1qY2NAdXe2RT+O 6nuNmVFzej5oUiMi1/2fFRxOKNHLn6tBO/v1MHckk8Rx+nod88q66SJ+OT0pM1/87G qqwDN6NUUd+nQ== Date: Sun, 4 May 2025 11:41:56 +0200 From: Ingo Molnar To: Steven Rostedt Cc: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, Masami Hiramatsu , Mathieu Desnoyers , Josh Poimboeuf , Peter Zijlstra , x86@kernel.org, Jiri Olsa , Namhyung Kim Subject: Re: [PATCH v7 00/17] unwind_user: perf: x86: Deferred unwinding infrastructure Message-ID: References: <20250502164746.178864972@goodmis.org> 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-Disposition: inline In-Reply-To: <20250502164746.178864972@goodmis.org> * Steven Rostedt wrote: > unwind_user: Add user space unwinding API > unwind_user: Add frame pointer support > unwind_user/x86: Enable frame pointer unwinding on x86 > perf/x86: Rename and move get_segment_base() and make it global > unwind_user: Add compat mode frame pointer support > unwind_user/x86: Enable compat mode frame pointer unwinding on x86 > unwind_user/deferred: Add unwind cache What is the cost of 'caching' here? Will we double-buffer the tracing data before it reaches its single primary tooling user, with no use of any actual 'caching', which will be scenario in like 99.9% of the everyday usecases when this facility is used? > unwind_user/deferred: Add deferred unwinding interface > unwind_user/deferred: Make unwind deferral requests NMI-safe > perf: Remove get_perf_callchain() init_nr argument > perf: Have get_perf_callchain() return NULL if crosstask and user are set > perf: Simplify get_perf_callchain() user logic > perf: Skip user unwind if the task is a kernel thread. Please don't leave periods in titles. Thanks, Ingo