From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from ale.deltatee.com (ale.deltatee.com [204.191.154.188]) (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 9575122ACE3 for ; Tue, 8 Apr 2025 16:57:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=204.191.154.188 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744131441; cv=none; b=ofiX1vm3jttoUmc8QlcLrbW5QMkFlJbXWxPdjCxUr/k7kgrswghUotjAnSyg92zvSRomSXPHpdVcHXNqx87fGLH9oaXrEdBtMGKHJP65Lot5q9wYkEgrDP2xitrf4aZukcE+UbPvEBZjU6j3Gm97tSGFJ9D4Z68qEc/n3mGMT5w= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744131441; c=relaxed/simple; bh=O0+17WUfEaHXbmjRQLD+nSND55dYNbv+rYx911yjSMU=; h=Message-ID:Date:MIME-Version:To:Cc:References:From:In-Reply-To: Content-Type:Subject; b=WhIAGO3IKws294vyTTZWQsQHNRJVebkqEWNu05cPLQnKUO4K+sK3QQOJDsUElK1gBRm22iW2iUQ2B3Jyzkdudp3yGstonoeo+vu1/sfDXsaukg5iWmwfQ5gzROOIueyPnI8OrLrUgVbwSxggw/1A7JLYkdIYHTHHKbZp2WDEJjg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=deltatee.com; spf=pass smtp.mailfrom=deltatee.com; dkim=pass (2048-bit key) header.d=deltatee.com header.i=@deltatee.com header.b=dMq/p+0w; arc=none smtp.client-ip=204.191.154.188 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=deltatee.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=deltatee.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=deltatee.com header.i=@deltatee.com header.b="dMq/p+0w" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=deltatee.com; s=20200525; h=Subject:In-Reply-To:From:References:Cc:To: MIME-Version:Date:Message-ID:content-disposition; bh=6J5HqLg7d0KAcqcPTq2XYRoxTDZiGcXuWLeV6rOZ7kg=; b=dMq/p+0wKouap7QG3kFDwk/SCs M7Bq74xkoRlBlWUtYXbhWZA6R6iMPpEZDVX9NsUX3Ll5mO4RXHYQj+offK5ldEjYKVjeQBKCRBea8 ILagV0JVq/Frmep+UfJL3pI8qiaiTZEQEfofQ3vgtqX72bWhi4pYFz8acoOOUsIIWwM+2ReV89oNy K5rM4PPv1Vo+05c5h/SPSf2d8EGYFN0WNlRJHvqXwD5LQwugIhL5EjzL9q8HdipW6ETblLy/FByiR AZvHFc9UsVwCF79hFWeF0VDUhuMDNF48wiK2vQOOFKHXNU4TrRcKdTM2lgPn7ocuyWBnl92nXh5ab RDVg3CoQ==; Received: from guinness.priv.deltatee.com ([172.16.1.162]) by ale.deltatee.com with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (Exim 4.96) (envelope-from ) id 1u2Bl3-0004Ac-19; Tue, 08 Apr 2025 10:25:06 -0600 Message-ID: <6695d513-3c0d-427f-96e5-79ada046cedf@deltatee.com> Date: Tue, 8 Apr 2025 10:25:03 -0600 Precedence: bulk X-Mailing-List: linux-pci@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird To: Lukas Wunner , Damir Chanyshev Cc: Bjorn Helgaas , linux-pci@vger.kernel.org, "Michael J. Ruhl" , =?UTF-8?Q?Ilpo_J=C3=A4rvinen?= References: <20250408150623.GA232275@bhelgaas> Content-Language: en-CA From: Logan Gunthorpe In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-SA-Exim-Connect-IP: 172.16.1.162 X-SA-Exim-Rcpt-To: lukas@wunner.de, conflict342@gmail.com, helgaas@kernel.org, linux-pci@vger.kernel.org, michael.j.ruhl@intel.com, ilpo.jarvinen@linux.intel.com X-SA-Exim-Mail-From: logang@deltatee.com X-Spam-Level: Subject: Re: P2PDMA support status for the sappire rapids+ X-SA-Exim-Version: 4.2.1 (built Wed, 06 Jul 2022 17:57:39 +0000) X-SA-Exim-Scanned: Yes (on ale.deltatee.com) On 2025-04-08 09:28, Lukas Wunner wrote: > On Tue, Apr 08, 2025 at 06:14:55PM +0300, Damir Chanyshev wrote: >> On Tue, Apr 8, 2025 at 6:06???PM Bjorn Helgaas wrote: >>> The pci_p2pdma_whitelist[] is only updated when somebody tests a >>> platform and determines that its RC can route peer-to-peer >>> transactions between separate Root Ports. This routing is not >>> required by the PCIe spec, so we can't assume that all platforms >>> support it. >> >> For the testing, is simple rdma ping-pong sufficient? Or a more >> specific testing tool? >> Unfortunately I don't have a fancy pcie hardware analyzer. > > You should test that performance is satisfactory for you needs. I couldn't have said it better myself. If you have any application running on a machine that uses P2P then that is sufficient testing in and of itself to add the machine to the list. My expectation is that any modern Intel root complex should work, but we don't have a concise rule that guarantees this so we are stuck in the unfortunate situation to add each family as they are tested by someone who cares about it. AMD confirmed for us that all modern devices will support P2P and provided a concise rule that works for all current and future devices. My limited experience with ARM devices suggest many root complexes do not support P2P, so they will likely always have to be added on a case by case basis. Logan