From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 3BCD248CD6E for ; Thu, 13 Aug 2026 16:05:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786637109; cv=none; b=Nju8UUpi3JtAoVm7c/PorRctnWvKYb65OEm5xjvg5VfYDUhDHxWPeurVU/xVyo7bKvi5U4kK/13fauVJumGvRDM1MTFQYBPJGysD/kCm7isvEniAstvZWZZC+K10vnv26OVlmAvSkZeOsDRWXHEdI4421NS4SLMFJzr83u0eho0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786637109; c=relaxed/simple; bh=CassZyB3CfPiImnR0NQX/XzYwGVV1P3P5xE3jYeq9oc=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=ROP41kBKoFraqbbP0Wh/Le0M9KubJzwMGE4oJXGtuhup4q0+ko/bYKKiuR+4uWpABUBNm4wwjGZCEpD3gB+5sh42xh48sRx6w/Zk2f4M9zWMTVAKPngbdADPPL10+dJ/HJemflr1hKt7Y7COgFUXAOri5l/7I/MNZ5uXYV+ECfA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b=TNOpS4YL; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b="TNOpS4YL" 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> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: 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> 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