From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.gentoo.org (woodpecker.gentoo.org [140.211.166.183]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E8CFC229B13; Wed, 2 Jul 2025 11:44:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=140.211.166.183 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751456700; cv=none; b=l2cMlviCfk4nZsjPX18J7B5x7UDh2jJt6VafYKwtvtyS/5tpuqAjMdW3Rvcxlu4WGKt/ZUbV25S/btC/Z3Odd41bbONoypPzK/xy1hOtRAJvCiewMG4cM2c43KEsXBtck7jOw0GG1BGK2f32aMCiiYQiJkg86u0q7fLCcpW3hRU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751456700; c=relaxed/simple; bh=8GKq3PK2RAXJflRfO6z7N1Qh8M5GuPT3A2ZYflG78hM=; h=From:To:Cc:Subject:In-Reply-To:Date:Message-ID:MIME-Version: Content-Type; b=UQM3GkzthEoD8dzGapx9fLhIO2Tf3VYqr8TvQeyk9qt9Vs1RFUJ/XHcDF1cQ13qDCRMaff2wdr2tuRMuM6VfzrDIAm6DUhLclGR61GCxsXJVAcil61CXCtAUCTv5lR7UssPfcN6zUtSfLnMP6xY2B6itFg2brHziA82wzw/MbgY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gentoo.org; spf=pass smtp.mailfrom=gentoo.org; arc=none smtp.client-ip=140.211.166.183 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gentoo.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gentoo.org Received: from mop.sam.mop (unknown [82.8.138.118]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange secp256r1 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: sam) by smtp.gentoo.org (Postfix) with ESMTPSA id 92323341ED4; Wed, 02 Jul 2025 11:44:54 +0000 (UTC) From: Sam James To: fweimer@redhat.com Cc: akpm@linux-foundation.org,andrii@kernel.org,axboe@kernel.dk,beaub@linux.microsoft.com,bpf@vger.kernel.org,indu.bhagat@oracle.com,jemarch@gnu.org,jolsa@kernel.org,jpoimboe@kernel.org,jremus@linux.ibm.com,linux-kernel@vger.kernel.org,linux-trace-kernel@vger.kernel.org,mathieu.desnoyers@efficios.com,mhiramat@kernel.org,mingo@kernel.org,namhyung@kernel.org,peterz@infradead.org,rostedt@goodmis.org,tglx@linutronix.de,torvalds@linux-foundation.org,x86@kernel.org Subject: Re: [PATCH v11 00/14] unwind_user: x86: Deferred unwinding infrastructure In-Reply-To: <878ql9mlzn.fsf@oldenburg.str.redhat.com> Organization: Gentoo User-Agent: mu4e 1.12.11; emacs 31.0.50 Date: Wed, 02 Jul 2025 12:44:51 +0100 Message-ID: <87wm8qlsuk.fsf@gentoo.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 I started to play around with this properly last night and it was straightforward, fortunately. Did initially attempt to backport to 6.15 but it was a victim of some mm refactoring and didn't seem worth to carry on w/ that route. Started a rough page with notes for myself (but corrections & such welcome) at https://wiki.gentoo.org/wiki/Project:Toolchain/SFrame but honestly, it's immediately obvious (and beautiful) when it's working correctly. I've used Namhyung Kim's example from this thread but you can see it easily with `perf top -g` too. In one of the commit messages in the perf series, Steven also gave `perf record -g -vv true` which was convenient for making sure it's correctly discovered deferred unwinding support. I plan on doing measurements next and doing some more playing once I've built more userland with it.