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 6831826D4E5; Tue, 2 Dec 2025 04:52:36 +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=1764651156; cv=none; b=Itg86dHBYpnhr4h6zSI00P+gLx/A89dampRH2Bplf0UFRcpTBxpj0dKB6kapkLnV+sUx5DHtMsOcelA13iURcKvR/JFqcqpkcST1FpyVm7ALsCI3cqz6XWogNvqTXi3SH3Uh848Y2PGAGw8hDNDr2JEy1REErKoRQ5XykAOBBio= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764651156; c=relaxed/simple; bh=WClWem7m6PcEoPPhzHb90N/2hEOUA1s0vWbVVK/4kKs=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=hiHFk/buLcC+13o0XF4hdL92hj6+eETTMmIy34zN5KLjfAB/XIypcVjqx3ote0aEWeAS2e+c4zwhPn04+T4ZaXSjt+1Y80aNlA/d/07IMf7XrkjvysbKJz2XdUmlf2uwNZBnnFYwGQgefpA+koa68AzWkcx7UNfVLGah3eilMRw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=WDtjBCii; 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="WDtjBCii" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 37D12C4CEF1; Tue, 2 Dec 2025 04:52:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1764651155; bh=WClWem7m6PcEoPPhzHb90N/2hEOUA1s0vWbVVK/4kKs=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=WDtjBCiizQbNOo8MgxH81F44TbOnpJK6ykdsq25KDX6WC7LdRuaM8tsph0CPBGu9G shZeSi/6bjhedtc0Z/HkKsthS6BQ+pAPxp8ZAmKy9aDr48zxFQQtG9etx4kO9elQ9L xHBYv4d7OjRcqNnaoWbmk5h/795qG8YzTR6IJIW5EIRboaUwKMEg0usbOyrhoDeDPo 15vwVm8ynmhVvAgxBTLRA6h9ov3BSWrV4tBuQ09rqbCoR3NO2qkyPGqAkrOqg0/EnR 8gqGXqeiWQxZOoHyMWWQBvZIlNxzv9TSPfMhodZjkR7mLZWE6ZllrpAbefgwJCN0EX enyA+ZRvfu5yg== Date: Tue, 2 Dec 2025 05:52:30 +0100 From: Ingo Molnar To: Ian Rogers Cc: Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Namhyung Kim , Alexander Shishkin , Jiri Olsa , Adrian Hunter , James Clark , linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v1 1/4] perf stat: Allow no events to open if this is a "--null" run Message-ID: References: <20251201230904.290733-1-irogers@google.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=us-ascii Content-Disposition: inline In-Reply-To: * Ingo Molnar wrote: > With all 4 patches applied to v6.18 'perf stat --null' > works fine: > > Tested-by: Ingo Molnar BTW., there's a long-standing perf-stat --repeat bug where signals don't seem to get properly propagated. The following command takes 10 seconds to run, as expected: starship:~/tip> perf stat --null --repeat 10 sleep 1 Performance counter stats for 'sleep 1' (10 runs): 1.0026669 +- 0.0000503 seconds time elapsed ( +- 0.01% ) But if I try to interrupt the test: starship:~/tip> perf stat --null --repeat 10 sleep 1 ^Csleep: Interrupt ^Csleep: Interrupt Performance counter stats for 'sleep 1' (10 runs): 0.9250 +- 0.0543 seconds time elapsed ( +- 5.87% ) The Ctrl-C only propagates to the , interrupts it (as can be seen from the shortened total runtime that is less than 10 seconds), and otherwise results in both an incorrect measurement and a misleading output of the partial results. Furthermore, the test runs to full completion - which can be annoying if you happen to use high --repeat counts like I sometimes do. I have to Ctrl-Z and killall -9 perf to kill such instances. Thanks, Ingo