From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from linux.microsoft.com (linux.microsoft.com [13.77.154.182]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 649C5258A; Fri, 30 May 2025 16:26:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=13.77.154.182 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1748622379; cv=none; b=bpu9B6BvTPxsUcEzy0lex4Y3ASBHjZeWHBf7V1msKteV2Lve4Chr1j2lrGv0DGqdibqpmxcJ+ZSxfYmMLPvUnWrsoBpnPfT0+Z+26vFHafhw5CJm8Q2afkYu7LuunzIJQP9PbnKcY2PplAZTQpQ6Wtrn4oLfLLCwVEfGzROy0zs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1748622379; c=relaxed/simple; bh=4gl8dUCffxbWT74cO0c8qTqtcjsb/ZE1Evms0ln2jU0=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=Mtazwsvr22co9Bu+ftW7HtyaNMQ45kM1+uxaHG9PrQaDi0dRSL7YzbSJbXgnD3TxfE5Dyp55sYZMsiajwivdQp/IFgRNUyAd6pTI4og51tOBakmVk2pRnBWuxd1uTshPlRvk6TIs88ESpC6tT1hKP1//k+pKa1mDitVXgopT0RY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.microsoft.com; spf=pass smtp.mailfrom=linux.microsoft.com; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b=VImXXTJ4; arc=none smtp.client-ip=13.77.154.182 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.microsoft.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.microsoft.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b="VImXXTJ4" Received: from [100.65.200.22] (unknown [20.236.11.185]) by linux.microsoft.com (Postfix) with ESMTPSA id A16E2203EE17; Fri, 30 May 2025 09:26:16 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com A16E2203EE17 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1748622376; bh=kKMCiJ564pe1xngnFVI97L6tQgSCXjivTIKDQLWSdJQ=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=VImXXTJ4G7YyU/cSHkqcyXm3pWm38kDsOdgfwLLmSjvicJeNqJdaHlIWmTUVSDKmD VDsdPMh8v+Xbkxz9980XHrVbw+zA1qnqYLVMFmOIryt2f4/joJGpnu3SiNz5OdVGET PrALftjTgvYIzv80I+q65qpkt74Wub6BQQUGK1w4= Message-ID: Date: Fri, 30 May 2025 09:26:16 -0700 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2] PCI: Reduce delay after FLR of Microsoft MANA devices To: Lukas Wunner Cc: linux-pci@vger.kernel.org, shyamsaini@linux.microsoft.com, code@tyhicks.com, Okaya@kernel.org, bhelgaas@google.com, linux-kernel@vger.kernel.org References: <20250528181047.1748794-1-grwhyte@linux.microsoft.com> Content-Language: en-US From: Graham Whyte In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 5/29/2025 3:34 AM, Lukas Wunner wrote: > On Wed, May 28, 2025 at 06:10:47PM +0000, grwhyte@linux.microsoft.com wrote: >> Add a device-specific reset for Microsoft MANA devices with the FLR >> delay reduced from 100ms to 10ms. While this is not compliant with the pci >> spec, these devices safely complete the FLR much quicker than 100ms and >> this can be reduced to optimize certain scenarios > > How often do you reset these devices that 90 msec makes a difference? > What are these "certain scenarios"? > VF removal and rescan is the main scenario for runtime repairs and driver updates. Doing this on scale with 100ms adds up to significant time across multiple VFs. > There are already "d3hot_delay" and "d3cold_delay" members in > struct pci_dev. I'm wondering if it would make sense to add > another one, say, "flr_delay". That would allow other devices > to reduce or lengthen the delay without each of them having to > duplicate pcie_flr(). The code duplication makes this difficult > to maintain long-term. > This is a good suggestion, we can make this more generic. > Thanks, > > Lukas