From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C6B2FC433EF for ; Thu, 27 Jan 2022 01:22:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234456AbiA0BWy (ORCPT ); Wed, 26 Jan 2022 20:22:54 -0500 Received: from mail.efficios.com ([167.114.26.124]:52402 "EHLO mail.efficios.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234416AbiA0BWx (ORCPT ); Wed, 26 Jan 2022 20:22:53 -0500 Received: from localhost (localhost [127.0.0.1]) by mail.efficios.com (Postfix) with ESMTP id D94AC363E3A; Wed, 26 Jan 2022 20:22:52 -0500 (EST) Received: from mail.efficios.com ([127.0.0.1]) by localhost (mail03.efficios.com [127.0.0.1]) (amavisd-new, port 10032) with ESMTP id gmMN3NZlGKwc; Wed, 26 Jan 2022 20:22:52 -0500 (EST) Received: from localhost (localhost [127.0.0.1]) by mail.efficios.com (Postfix) with ESMTP id 8CEEA36364A; Wed, 26 Jan 2022 20:22:52 -0500 (EST) DKIM-Filter: OpenDKIM Filter v2.10.3 mail.efficios.com 8CEEA36364A DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=efficios.com; s=default; t=1643246572; bh=WhNg8N27gF3iN7GhFfsYWyunl7sLSzaowOAX4hMmAOk=; h=Date:From:To:Message-ID:MIME-Version; b=ksTPZa3S+qK6YhDekMwQ0stz2dWonSKhqPS0WNseabD2jtYgYHEj4WIPOc1/wJq7f M3hzH0N9kk9tc5dkSqfn38+YlbE0BBn9sIPJ3LwLGR5GC2lqYeuIn8lWAq2/4MYzl5 6QoF4wpooCkqr4A7+7UgwwaxI3QGWK+q1ZrO24VBxJQa6Uxuxyz2kOxc5wmRlrY6qQ r5lsjkeL7PEFprPRnI5DGQYWCuzzWdE8844/JkbPykO/8vy/ghsTljIems7szS/ucs X5QwfcQz6TWHm9MCvbbh6gHEcxs13wtJ8GvRHN/jU6RHFXVPDzgCIGeEDCxa1jLaJe 829Sh+3KRSRlA== X-Virus-Scanned: amavisd-new at efficios.com Received: from mail.efficios.com ([127.0.0.1]) by localhost (mail03.efficios.com [127.0.0.1]) (amavisd-new, port 10026) with ESMTP id Ewz4yBBKn4A1; Wed, 26 Jan 2022 20:22:52 -0500 (EST) Received: from mail03.efficios.com (mail03.efficios.com [167.114.26.124]) by mail.efficios.com (Postfix) with ESMTP id 7ECD5363649; Wed, 26 Jan 2022 20:22:52 -0500 (EST) Date: Wed, 26 Jan 2022 20:22:52 -0500 (EST) From: Mathieu Desnoyers To: Paul Turner Cc: Peter Zijlstra , Michael Jeanson , paulmck , Boqun Feng , linux-kernel Message-ID: <1211272108.4257.1643246572499.JavaMail.zimbra@efficios.com> Subject: rseq vcpu_id ideas MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-Originating-IP: [167.114.26.124] X-Mailer: Zimbra 8.8.15_GA_4203 (ZimbraWebClient - FF96 (Linux)/8.8.15_GA_4203) Thread-Index: ix/xoRPtt8dW/JcuQ/MP/FnBqGa3UA== Thread-Topic: rseq vcpu_id ideas Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Paul, I remember our LPC discussions about your virtual cpu ids ideas, and noticed some tcmalloc code with "prototype" fields for vcpu_id and numa node id (https://github.com/google/tcmalloc/blob/master/tcmalloc/internal/linux_syscall_support.h#L34). I'm currently toying with ideas very close to vcpu_ids to solve issues with overzealous memory allocation for LTTng-UST (user-space tracer) in use-cases where containers use few cores. My current thinking is that we could use your vcpu_id idea, but apply it on a per-pid-namespace basis rather than per-process. We may have to be clever with NUMA as well to ensure good NUMA locality. Do you have any thought about this, and perhaps some prototype rseq extension code you could share as a starting point ? Thanks, Mathieu -- Mathieu Desnoyers EfficiOS Inc. http://www.efficios.com