From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 32D222D59E8; Fri, 6 Feb 2026 16:32:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770395546; cv=none; b=o7Glu+4awOyuY3jAMCbICiYs9lH9pztcsMoxmwW6bWTWqEeGpikylNw7/h/C0dXJZDTVJCOg35BK9hrgHyM+DQNpGN+gmd/0Tp5CZLZCEbnJv8/M64fguD4usamQoSW5Z0nkdSacuqP9iv7aZJ01hZy6gd5D22N65cOmkyqGVjY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770395546; c=relaxed/simple; bh=pLj5gfSpPNhHMqK08AguxHM0bMKKBT3fh/AiiFMTCo0=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=JQ7x7YveMAphVaLZQ0mtX5ymdWx040xrSc4YEIwjdgtfv4h1R7Jikekit8TIdWfIfWRVl5g7M9RKxeS4qwkbRTArNm2eoGb8MTYZKPZhrfrqPg81jAtFkAHn4nlLJ3uKuem2Qip/nauNeBnLO1t67oRUfJSoKpEvW5J8ld9Y+6g= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 4C8E4339; Fri, 6 Feb 2026 08:32:19 -0800 (PST) Received: from localhost (e132581.arm.com [10.1.196.87]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 398C13F632; Fri, 6 Feb 2026 08:32:25 -0800 (PST) Date: Fri, 6 Feb 2026 16:32:22 +0000 From: Leo Yan To: Ian Rogers Cc: Arnaldo Carvalho de Melo , Namhyung Kim , Jiri Olsa , Adrian Hunter , James Clark , linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] perf record: Make logs more readable for event open failures Message-ID: <20260206163222.GH3529712@e132581.arm.com> References: <20260204-perf_improve_log_for_open_event_failures-v1-1-150245792810@arm.com> Precedence: bulk X-Mailing-List: linux-perf-users@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On Thu, Feb 05, 2026 at 02:33:04PM -0800, Ian Rogers wrote: > On Thu, Feb 5, 2026 at 1:42 PM Arnaldo Carvalho de Melo wrote: > > > > On Wed, Feb 04, 2026 at 09:29:14AM -0800, Ian Rogers wrote: > > > On Wed, Feb 4, 2026 at 6:26 AM Leo Yan wrote: > > > > > > > > Since commit ee27476fa300 ("perf record: Skip don't fail for events that > > > > don't open"), if a user does not have permission to access a PMU event, > > > > perf reports: > > > > > > > > perf record -e cs_etm// -C 3 -- ls > > > > Error: > > > > Failure to open event 'cs_etm//u' on PMU 'cs_etm' which will be removed. > > > > No fallback found for 'cs_etm//u' for error 13 > > > > Error: > > > > Failure to open event 'dummy:u' on PMU 'software' which will be removed. > > > > No fallback found for 'dummy:u' for error 13 > > > > Error: > > > > Failure to open any events for recording. > > > > > > > > The log is not very helpful, as no clear indication of what "error 13" > > > > means or how to address the issue. > > > > > > > > This commit restores evsel__open_strerror() to generate a readable error > > > > message and print it out: > > > > I'm applying this one, maybe we can at least suppress the one for dummy > > when it is auto added? > > IIRC it was left in as "perf record -e dummy" can be a way of just > tracking sideband data and you'd want errors opening dummy to be > warned upon in that case. As Arnaldo said this patch has been picked, I sent a following patch for simplifying the logs: https://lore.kernel.org/linux-perf-users/20260206-perf_improve_log_for_open_event_failures-v1-1-366903bebcd7@arm.com/T/#u If want me to resend two patches in a series, or squash into one, please let me know. Thanks! Leo