From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtpout.efficios.com (smtpout.efficios.com [167.114.26.122]) (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 4BF6A5D724 for ; Wed, 13 Mar 2024 23:24:37 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=167.114.26.122 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1710372282; cv=none; b=QUlND8/mlclXjXTCJobDh3ao3g7rQcNaftyzWfqCgXASqon/oYsaw0FUOYwQb5h5s/N91c0rIv1dyYwXpyTWJoC8SOJKxIhaGe9X4IvTHRUX+YKb9oPBZrKNarXG/7U0d1SuVHjLCjqPqo2WxhDdGuHBJ0KSVwLnoRJsgctphFU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1710372282; c=relaxed/simple; bh=HKyUwew810z+LaXSBYXDklPZLMcXYEepc/mtYjT8i2E=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=i9PAzBSwGRdh30wQdoYfm7Qaf1o3ipeUgv77eS5SAlXY8vpRXfHpDCTiWAkkiKEN5Il98TJCU1o5KjpYsWMfLvOwzCLUOXXhhDXmYrIue8AQrNqRCrxptvlIqYToSDsOYb0YdPFW7/rgJGdSZ4nCd+b3rK7vv6P3MauGIpwmdCY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=efficios.com; spf=pass smtp.mailfrom=efficios.com; dkim=pass (2048-bit key) header.d=efficios.com header.i=@efficios.com header.b=TCBS+aCQ; arc=none smtp.client-ip=167.114.26.122 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=efficios.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=efficios.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=efficios.com header.i=@efficios.com header.b="TCBS+aCQ" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=efficios.com; s=smtpout1; t=1710372275; bh=HKyUwew810z+LaXSBYXDklPZLMcXYEepc/mtYjT8i2E=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=TCBS+aCQYGgS3gC+Ki41nQJO4zxg6uQPSswbzaNoPTgpUCUlRv5c/TeC9zS38FDDQ 2n/IphpS4HGVoDbxePU3oyPpwKIGkNzZZAjqxBicnCcjrAI3AuC368t2xB3hNvKLQr emhIB87ZUfGHemL7vbSGH4YGlmF2k/ICd8Pq4JgD7ioMnxiu2UfUUOJTeeerdv3s3U c2+u8L0i4JAeo+6hGe3PiyF5HuQxLYL4ZV9MtEDu/ESGduNRghYRyewy906+zuqaYe TRfjYEF1htGgn9d7TA8eKTpcEw4LqY0tyeUnpB68FI/V2z9IVs22iMpq7p0vXcqBhP DdW3eK+BPAP/g== Received: from [IPV6:2606:6d00:100:4000:cacb:9855:de1f:ded2] (unknown [IPv6:2606:6d00:100:4000:cacb:9855:de1f:ded2]) by smtpout.efficios.com (Postfix) with ESMTPSA id 4Tw66W60PkzjcJ; Wed, 13 Mar 2024 19:24:35 -0400 (EDT) Message-ID: <65d88186-7975-46ff-aef9-3b3a34f8e97a@efficios.com> Date: Wed, 13 Mar 2024 19:24:49 -0400 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH 1/2] smp: Implement serialized smp_call_function APIs Content-Language: en-US To: Linus Torvalds Cc: Peter Oskolkov , linux-kernel@vger.kernel.org, Peter Zijlstra , "Paul E . McKenney" , Boqun Feng , Andrew Hunter , Maged Michael , gromer@google.com, Avi Kivity , Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman References: <20240313205622.2179659-1-mathieu.desnoyers@efficios.com> <20240313205622.2179659-2-mathieu.desnoyers@efficios.com> From: Mathieu Desnoyers In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 2024-03-13 17:19, Linus Torvalds wrote: > On Wed, 13 Mar 2024 at 13:56, Mathieu Desnoyers > wrote: >> >> Introduce serialized smp_call_function APIs to limit the number of >> concurrent smp_call_function IPIs which can be sent to a given CPU to a >> maximum of two: one broadcast and one specifically targeting the CPU. > > So honestly, with only one user, I think the serialization code > should be solidly in that one user, not in kernel/smp.c. Good point, unless other users of this show up, I could move it into membarrier.c. But only if anyone cares enough to come up with benchmarks justifying the added complexity. > > Also, this kind of extra complexity does require numbers to argue for it. Of course, Thanks, Mathieu > > Linus -- Mathieu Desnoyers EfficiOS Inc. https://www.efficios.com