From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) (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 923251FFC43 for ; Thu, 27 Mar 2025 08:10:46 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=193.142.43.55 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1743063048; cv=none; b=ASxfKbDBuQPjVMbizPwF1g9pKKhgSXNG/arEdX9PflXz76Cm/ZPIumbtn1v0o1N2XqxyFkffRm7cYXKjwfl1ES+7yNc/jvFE2dQOPOTJIJM4unqc332dwM2tvTDveumyb0s8rpYpiZCT587RhAZXlbR7AMtmDGuzVQY3IQJqQNA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1743063048; c=relaxed/simple; bh=Ok6sbhuAHQgOj0VCWpsrZDM5gqJfXhwA7DaUP3dLmD4=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=B+3zIW1U3oOMEsKf+7B0JiIxYaZgVg2wiqQQ+mwOZpTqE7nRoEOY3hzITe6N7P+uWTkXP3NND5l7Hscxa68y7L/GZAnqdNmyrZUw8GJub90t/TYWvtw0qNP5+VRAyionujarWJHZMJ0GO68patojAqQ4K1OCA25igCvs60dYkIc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de; spf=pass smtp.mailfrom=linutronix.de; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=OX0DLUrl; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=o+qzkT+6; arc=none smtp.client-ip=193.142.43.55 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linutronix.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="OX0DLUrl"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="o+qzkT+6" From: Thomas Gleixner DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1743063044; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=hKLZQkdc4yEMpxWrE9FAL8M+lw5YXUz3sNPr4J+7xHU=; b=OX0DLUrlW+fgg5NnLkdMX53EVPjOBtgQZTbnXRiyEg+ITLbebuSKU6OSInDWxVutaf+9iD 9o9J5Z9kYnc9K8BQvue0zb1JPXOzlP0x5FbIg87InVQbkLgLG6A8lCjGYMUCGXzeW1rXK+ YSqyZZFu3rbbNkQprdoF2dmOa5yIO1tK3S+iLQXd0xnv+KVW5K2TCasXe1sT7900yDDJAd hzgDdz9HeU+qXthyhvqG/JFeZMrqKkkBgYZRF97foX99JXtRst1S90KtyAk4y1o2wleqHR aM/rwW6H9VjtWV+8c3b7xxKnEU3gjWKkO2xlTJg3uImAoHcv9X5XfoOrADwx2A== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1743063044; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=hKLZQkdc4yEMpxWrE9FAL8M+lw5YXUz3sNPr4J+7xHU=; b=o+qzkT+6oSMCd+hmHu1f9f+3QPwQAX/BmaGuV+qdKtl43dl3LiWMsQa2Z4wuwoBiwa9SlI g3IeWjmlQoolRJDQ== To: Eric Dumazet , Mateusz Guzik Cc: kernel test robot , oe-lkp@lists.linux.dev, lkp@intel.com, linux-kernel@vger.kernel.org, x86@kernel.org, Benjamin Segall , Frederic Weisbecker Subject: Re: [tip:timers/core] [posix] 1535cb8028: stress-ng.epoll.ops_per_sec 36.2% regression In-Reply-To: References: <202503241406.5c9cb80a-lkp@intel.com> <87pli4z02w.ffs@tglx> <6sn76aya225pqikijue5uv5h3lyqk262hc6ru3vemn7xofdftd@sw7gith52xh7> Date: Thu, 27 Mar 2025 09:10:44 +0100 Message-ID: <877c4azyez.ffs@tglx> Precedence: bulk X-Mailing-List: oe-lkp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable On Thu, Mar 27 2025 at 07:21, Eric Dumazet wrote: > On Wed, Mar 26, 2025 at 10:11=E2=80=AFPM Mateusz Guzik wrote: >> On Wed, Mar 26, 2025 at 09:07:51AM +0100, Thomas Gleixner wrote: >> > Unfortunately I can't reproduce any of it. I checked the epoll test >> > source and it uses a posix timer, but that commit makes the hash less >> > contended so there is zero explanation. >> > >> >> The short summary is: >> 1. your change is fine > > Let me rephrase this. > > Absolutely wonderful series, thanks a lot Thomas for doing it. Thank you! > Next bottlenecks are now these ones, but showing up in synthetic > benchmarks only. Right. I saw them too when working on this. > 33.36% timer_storm [kernel.kallsyms] [k] > inc_rlimit_get_ucounts > > 32.85% timer_storm [kernel.kallsyms] [k] > dec_rlimit_put_ucounts These two are not really posix-timer specific. They are also the standouts for any signal micro benchmark. I stared at the implementation a bit, but there is not much we can do about that I fear. Thanks, tglx