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 lists.lttng.org (lists.lttng.org [158.69.130.29]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id D8B1FC36000 for ; Fri, 21 Mar 2025 14:10:48 +0000 (UTC) ARC-Filter: OpenARC Filter v1.2.1 lists.lttng.org 4ZK49L6Bt5z155b ARC-Seal: i=1; d=lists.lttng.org; s=arc1; a=rsa-sha256; cv=none; t=1742566248; b=TKz9NM8Cp1HSHRnbYCACvwXzbQYuaPZDqJ7vEFjeoKa9XK+622Me2aRU6GDxIZYwmI9U QUNUhNqn48pDvrkvng4etvGWzAz9DMFsrZISsbHdK/ghDS9CrrDDdUlH1eJI/TNsGnfWO 2UcuZRXhhFP0Vr8L2A3YIIXfsVVkxDCUT6ZmdSf0v9pm0VM2P0L5WIaE1+mBoN71tDv60 5y1BKXH4XL/uHl84zIzi5xurenF2AgaVD3o7kM71348+Hy3G45Uwx5P4polIrINvDEj+V kntBkvKiBgq4Yk/Funxqwu1NeFvvf5wMVFlx087oyce+rZOSGp08Iu/2k/tiVC28hQQ== ARC-Message-Signature: i=1; d=lists.lttng.org; s=arc1; a=rsa-sha256; c=relaxed/simple; t=1742566248; h=DKIM-Signature:To:Subject:Date:Message-ID:MIME-Version:From:From; bh=GnvvywXot0MwlHCmh81YQUgyXK7kauxhxVWdEgBMooQ=; b=grdo9vDRH5kY8VsK2bNu09bQAc1cn4WicdfWFswqfYigeUQCRQ5VT5ILcWNvnxYQYJjW BScI7YN5j+HaYa92hiHdnv3XxFAugmjzMj2Ugst12Quw6GvK7P6mFHPjjDp/JzKgX5nGu CPDSRF3WLivwiM/5hn+XqvQ9agrTbBEF280B72uyk6vnG7hyP9x3bwfdqH6n9mfVoBrFy FupUi0Fy3aCgNBd7nIt6gpZ2wkwAxJyAfl54//Imh8RlT0XlRsDId3WI+Z+msMfs65QLZ VX0j3apeTUU0agcwmybnXJ++iWsDegmtj7MQG0pcPsdn7jxsSHUMShukbWF5ACWrKRg== ARC-Authentication-Results: i=1; lists.lttng.org; arc=none smtp.remote-ip="::1" DKIM-Filter: OpenDKIM Filter v2.11.0 lists.lttng.org 4ZK49L6Bt5z155b DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=lists.lttng.org; s=default; t=1742566248; bh=GnvvywXot0MwlHCmh81YQUgyXK7kauxhxVWdEgBMooQ=; h=To:Subject:In-Reply-To:References:Date:List-Id:List-Unsubscribe: List-Archive:List-Post:List-Help:List-Subscribe:From:Reply-To: From; b=FIQSgbaxUNuG2GUgKvgmjQCpjNgbMR4lO+okfKYkegYEJ3pOm/mjexGtbEJCeC0mC GLaHQs5sHXae5DHRoig0BiVXpNs66V6JD/dd0a3vBS1HDu1XRqos+rSo5J0S+yCX3h 24GLOyafKvIJsyndx3rPBCp1t4UMRvtabj4CdlTQVOvYMYnvz/GIMwlA04+GwV4j0O DW3H8ViCoUJO/Gc9PuTMKqHNu4vae1zK9gCuHfu1umh/pkVg6g5ftkcARd8rue22IC A8/UDLphNc87OOZE2fjmNOTBaDWZ2A/ZATuYYnOq54EmQ9wOnnomvtslnRXl6girng I9AVFNRGVo/Dg== Received: from lists-lttng01.efficios.com (localhost [IPv6:::1]) by lists.lttng.org (Postfix) with ESMTP id 4ZK49L6Bt5z155b; Fri, 21 Mar 2025 10:10:46 -0400 (EDT) ARC-Filter: OpenARC Filter v1.2.1 lists.lttng.org 4ZK49K3FFVz155Y DKIM-Filter: OpenDKIM Filter v2.11.0 lists.lttng.org 4ZK49K3FFVz155Y Received: from smtpout.efficios.com (smtpout.efficios.com [158.69.130.18]) by lists.lttng.org (Postfix) with ESMTPS id 4ZK49K3FFVz155Y for ; Fri, 21 Mar 2025 10:10:45 -0400 (EDT) Received: from localhost (199-193-172-8.cpe.axion.ca [199.193.172.8]) by smtpout.efficios.com (Postfix) with ESMTPSA id 4ZK49J4qRcz42Z; Fri, 21 Mar 2025 10:10:44 -0400 (EDT) To: Kienan Stewart , Gour DEV , lttng-dev@lists.lttng.org Subject: Re: lttng-dev Digest, Vol 203, Issue 7 In-Reply-To: <09086109-a0fd-4b38-817e-b5bd2cbd9c2f@efficios.com> Organization: EfficiOS References: <605bbc18-bb08-4a72-b470-fc0c34e67acd@efficios.com> <09086109-a0fd-4b38-817e-b5bd2cbd9c2f@efficios.com> Date: Fri, 21 Mar 2025 10:10:44 -0400 Message-ID: <87pliamq3f.fsf@laura> MIME-Version: 1.0 Content-Type: text/plain X-BeenThere: lttng-dev@lists.lttng.org X-Mailman-Version: 2.1.39 Precedence: list List-Id: LTTng development list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , From: Olivier Dion via lttng-dev Reply-To: Olivier Dion Errors-To: lttng-dev-bounces@lists.lttng.org Sender: "lttng-dev" On Fri, 21 Mar 2025, Kienan Stewart via lttng-dev wrote: > Hi Lakshya, > > On 3/21/25 8:52 AM, Gour DEV wrote: >> Thanks Kienan for digging this and explaining the behaviour, [...] >> Also, I thought using --buffers-global >> >> would >> be better for me as I could know how much memory will be required but looks >> like that option is only available for kernel tracking, it would be very >> good if this option could be available for user buffering also, but that >> could come later. >> > > Global buffers for UST is planned for the next release. The trade-off of > using it is that tracing overhead will increase (as the buffers are no > longer per-CPU), but in exchange for a potentially lower memory > footprint particularly in situations where not all possible CPUs are online. > Little correction here. `--buffers-global' is the ownership of the buffers (UID vs PID vs system). The next release introduces the buffers allocation policies `per-{cpu,channel}'. Therefore `--buffers-global' will still be only available for the kernel domain, AFAIK. User-space however will be able to allocate a single ring-buffer for a given channel (actually it depends on the buffer ownership UID vs PID), thus reducing the amount of memory used, for that channel, by a factor proportional to the number of CPUs possible on the system. [...] Thanks, Olivier -- Olivier Dion EfficiOS Inc. https://www.efficios.com