From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 E65D0305E32 for ; Fri, 22 May 2026 16:03:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779465831; cv=none; b=IlgY5JW1pHZUhl1+UDG2CzLrSE+QIRwUFaIJUOH7oOFRSj/vUa7pDZIy3nwq6V900XAxeYaXkTZTR1oavhHJ0AalE+hfkbx6AH9n85UCb3WHyakp3EbO8ezOArT94z9GKrJMnaS2U1qbkypdkfY0MI20romVeRWFLZMDkwTZL8o= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779465831; c=relaxed/simple; bh=qPwFpOw9l4pQgleHwB1p3vNnpQOiIQDkXte8YFQNB/8=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=sz9hh7SZ63DwLiJDnqRjLqMyYaq8eR/2AVtIPSIcJxioTkxv1R4UFi5usjy2Myyvp1o6Vyqa56DnEThP5Fg5N38E/SN4ub2+GFQmYTXy2WrVJqSfydY49RlYUh20UNlnN4r/q3+uW24bEV6RydGvYx/BL/UsyeNtvzJas7DvGpM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Wgn6mffB; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Wgn6mffB" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 05BAB1F000E9; Fri, 22 May 2026 16:03:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1779465830; bh=qoSiNm1A/GX7sVY/uzda7tY9wcM+GSdOO606XKEeZoE=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=Wgn6mffBhCwzB3oVtylTVWBUwSRbbfktpl1srUgEBdGCyKsIEDYSvkSw6F2gRl9Bm O5TlXGMbCQgY0w0OLz5JLlpXYWHdr3XLK+IGCCWfyL9FtObXmRyZyAibf5jDT2sQji zLfQWcDnmYYXfXzeyR284FNP4Lr5yiVd2xTmOWEgagfY0OLW5U+LDQF72ukY+nJsgw ltOwncA5k0V6Vv213X0qbFxnbxvsuVD3AdLzzK7urKSIS6Hs4DImi/Kgxs4l1ahs2b IQyF2ED/cxlkCu+ujkRMmRavBV36PytID7tSKx7vQIZsUIm4uHYw1qKv3PIkTxl1fT 3U9cSdZzWdfBQ== Date: Fri, 22 May 2026 09:03:47 -0700 From: Namhyung Kim To: Steven Rostedt Cc: Ian Rogers , linux-kernel@vger.kernel.org, Masami Hiramatsu , Mark Rutland , Mathieu Desnoyers , Andrew Morton , Arnaldo Carvalho de Melo , Jiri Olsa , Peter Zijlstra Subject: Re: [for-next][PATCH 10/15] tracing: Allow perf to read synthetic events Message-ID: References: <20260522143508.298439732@kernel.org> <20260522143526.523134137@kernel.org> <20260522114126.5df2f008@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=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20260522114126.5df2f008@gandalf.local.home> Hello, On Fri, May 22, 2026 at 11:41:26AM -0400, Steven Rostedt wrote: > On Fri, 22 May 2026 08:19:36 -0700 > Ian Rogers wrote: > > > On Fri, May 22, 2026 at 7:35 AM Steven Rostedt wrote: > > > > > > From: Steven Rostedt > > > > > > Currently, perf can not enable synthetic events. When it does, it either > > > causes a warning in the kernel or errors with "no such device". > > > > > > Add the necessary code to allow perf to also attach to synthetic events. > > > > Thanks so much for doing this work! I hoped to spend some time testing > > it, but there's never enough time. For the synthetic event I was > > I totally understand not having time. Heck, I'm currently unemployed and > I'm still having a hard time finding time! :) > > > wondering what values end up in the perf sample like 'period'? I can > > You mean to poll on the event? > > > imagine this being the case and that, if you are doing something like > > a futex wait duration, having to interpret the raw data rather than > > just getting aggregation for free in `perf report` via the period. > > That's not wrong but I was just curious. > > I guess I'm not quite sure what you mean by "the period". But then again, I > don't use perf that much. Oh, it's about the value of the event. IIUC, the period of any tracepoints is the number of times it hits. Using a field of tracepoint instead needs interpretation of the event. Thanks, Namhyung