From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 D452E2AD13 for ; Mon, 5 Aug 2024 19:10:00 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722885000; cv=none; b=CKsEb9rzaU/2UKB3T0f66pvtU1Xj5p2u9mINY6T2TJmBUhGsfvMuhIiAyJ2DnNjwhM645Z+CAue7QrJwXvzgImBILGX4xa6PWSobk8K+MQqTNDpQUmH/JB52KnB47af/j0WO4MT1hJOjagaTFWcA+sCCHhDE6/cyok6IvX1YXdY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722885000; c=relaxed/simple; bh=5MWJ+hkhvIBMmv6d0zCuMirXiJ9AU/CMw6EDAS06MCQ=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=ajQyMTKAdbYnR5NwlYm4s6BRZuvUIWiARUKeCyEbjwFZmW5Hzs85O+Bpj/bLLlSH5VWfRlVXYIkyMubAo7K62an1ZwrzWBSGrtGs1WNdqdcjk29xgeeQUHVZQZmxwHCmSx8ZRNALTET+txOol0bWjpa+pvgwGWYonVeSHvayFrI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=nC3oh9sy; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="nC3oh9sy" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 289C8C32782; Mon, 5 Aug 2024 19:10:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1722885000; bh=5MWJ+hkhvIBMmv6d0zCuMirXiJ9AU/CMw6EDAS06MCQ=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=nC3oh9syqpKA1/6Z6ncLUiSZcJ0RY4XkOIaUIDmQDmcY+UuA8BPaWBpvLxncVVTVy jghLAHTNGGy+4W6t1xiJ3uei6RQYUygzg/XzyDCCI22Hdt9Im84v3YdZ5QltXtUR0k bLjreWCstR3lWrAX8JRiQxpj0J7QJJE1EvnklZzrcAO+la45KVosfqZ7xZqFfb7HZf mWmtCvzuMS55sxdwTjXoe4VTJwSr7FPIh8vJBbS1KMAm47bEBaYIlG/y6ndOieVnZ9 UwkwW31/U1ce6OYqALsixTOYeIiVeavWcS3D2G+K6TSHqXkifXBySnm//gJ/8zDOgb Djk14xTfB+H2Q== Date: Mon, 5 Aug 2024 12:09:59 -0700 From: Jakub Kicinski To: Nick Child Cc: netdev@vger.kernel.org, bjking1@linux.ibm.com, haren@linux.ibm.com, ricklind@us.ibm.com Subject: Re: [PATCH net-next 7/7] ibmvnic: Perform tx CSO during send scrq direct Message-ID: <20240805120959.70608deb@kernel.org> In-Reply-To: <2ee7dd51-c45a-494e-ae24-b47fa938d321@linux.ibm.com> References: <20240801212340.132607-1-nnac123@linux.ibm.com> <20240801212340.132607-8-nnac123@linux.ibm.com> <20240802171531.101037f6@kernel.org> <2ee7dd51-c45a-494e-ae24-b47fa938d321@linux.ibm.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Mon, 5 Aug 2024 08:52:57 -0500 Nick Child wrote: > On 8/2/24 19:15, Jakub Kicinski wrote: > > On Thu, 1 Aug 2024 16:23:40 -0500 Nick Child wrote: > >> This extra > >> precaution (requesting header info when the backing device may not use > >> it) comes at the cost of performance (using direct vs indirect hcalls > >> has a 30% delta in small packet RR transaction rate). > > > > What's "small" in this case? Non-GSO, or also less than MTU? > > I suppose "non-GSO" is the proper term. If a packet is non-GSO > then we are able to use the direct hcall. On the other hand, > if a packet is GSO then indirect must be used, we do not have the option > of direct vs indirect. It'd be great to add more exact analysis to the commit message. Presumably the change is most likely to cause trouble in combination with large non-GSO frames. Could you measure the perf impact when TSO is disabled and MTU is 9k?