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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 D174EC5CFCF for ; Thu, 13 Aug 2026 16:05:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=CassZyB3CfPiImnR0NQX/XzYwGVV1P3P5xE3jYeq9oc=; b=jCb1I5Zn4+TuDsP4XOUiIKJYqE Qfz/vONYIz7+W2NamZlAhOkwtUg22vsJv6oX3L6cPVZmesL5cpyn9E00FznWEk1JYIBaetfzGjgD/ pMkHS9OrFAgh7iyob57sc0Ua4ed7nLWbLeizt0zYpQJss0fUS+dWWGwKk1IkXlHqnGZf+6A3Ir1pq loVYUpYQ0IImpgt4xk1PL49AnT1a/q1U/+pxcF6OUFWs9xGtHAt1qglfkQNoCUabWu9NfWjhARHhv o/IeOvwMfGGbSXDWD4XZlfNlmxGzhL8IfsCqCZSnVkWEJBuyuYhPCiidJt++6kAZjmlFsRhlbqVsm ZU1Oey3Q==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wuXvc-000000016e5-0gIS; Thu, 13 Aug 2026 16:05:12 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wuXvZ-000000016dH-1VdL for linux-arm-kernel@lists.infradead.org; Thu, 13 Aug 2026 16:05:10 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 83FDB1576; Thu, 13 Aug 2026 09:05:03 -0700 (PDT) Received: from localhost (unknown [10.2.196.114]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 0E3C33F66F; Thu, 13 Aug 2026 09:05:06 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1786637107; bh=CassZyB3CfPiImnR0NQX/XzYwGVV1P3P5xE3jYeq9oc=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=TNOpS4YLTIhs6sVykm2n3NBT0qKRfMV0QbHUYZyj1BaeXI8ZwRwxiaVivxOfGF0Tj p/rw4rgsNzWOoX1ifg+eKC7MNn7Xg/yNRscpdnf1LvqmIiHeYmONNSahN4m65+UAdN Y9bJ3go5VikudayYlqIgMT86FbnueQURnaa8+kR8= Date: Thu, 13 Aug 2026 17:05:04 +0100 From: Leo Yan To: James Clark Cc: Suzuki K Poulose , Mike Leach , Suyash Mahar , Yeoreum Yun , Greg Kroah-Hartman , Qi Liu , Junhao He , coresight@lists.linaro.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Jonathan Cameron Subject: Re: [PATCH v3 4/8] coresight: tmc-etr: Prevent per-thread events from sharing a sink Message-ID: <20260813160504.GC8904@e132581.arm.com> References: <20260728-james-cs-multiple-per-threads-v3-0-6aee7579f1dc@linaro.org> <20260728-james-cs-multiple-per-threads-v3-4-6aee7579f1dc@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260728-james-cs-multiple-per-threads-v3-4-6aee7579f1dc@linaro.org> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260813_090509_452599_9D70047D X-CRM114-Status: GOOD ( 10.90 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tue, Jul 28, 2026 at 04:00:16PM +0100, James Clark wrote: [...] > The identity and compatibility of a session are determined by the owning > process, the target process, and the inheritance settings together. Could you elaborate a bit on the session model you are trying to support here? My understanding of a legacy sink such as ETR/ETF is that it can be owned by only one perf session at a time. Multiple events belonging to that session may use the sink, but an attempt from another perf session should be rejected with -EBUSY. For per-thread mode, I wonder if we could support _only_ non-inherited events. In that case, we would not need to determine compatibility based on the target process and inheritance settings. >From the patch, it seems trying to support a more flexible model, where an already active legacy sink can also be shared by another perf session and also support inherit mode for child events? Thanks, Leo