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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D6D2EC433EF for ; Fri, 12 Nov 2021 10:09:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BBF8C60F70 for ; Fri, 12 Nov 2021 10:09:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234911AbhKLKM3 (ORCPT ); Fri, 12 Nov 2021 05:12:29 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]:29250 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234927AbhKLKMZ (ORCPT ); Fri, 12 Nov 2021 05:12:25 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1636711774; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=GpT2YYqG29Jg+Uxsx2CrH+IJrT+DNnW+q/s5xR+/nO8=; b=chVFhlOEM41HG0kWG6eKDS1G72jpwZJGtAftfbZNpxxeOmEjE0H84QQ4X1POkl6SfrCGth P78XMJRGbmDbZ0HRojHfKOMgx+VbAsZQDp9SSOCbh03igWTQuepyuPl7bsvuE/U5jVXQjS +2AKDDz6Byud0DTUP0EheioJPkl2Zrs= Received: from mail-ed1-f70.google.com (mail-ed1-f70.google.com [209.85.208.70]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-371-l2QdQiQ1OyaVDBzP6sOEhQ-1; Fri, 12 Nov 2021 05:09:34 -0500 X-MC-Unique: l2QdQiQ1OyaVDBzP6sOEhQ-1 Received: by mail-ed1-f70.google.com with SMTP id d11-20020a50cd4b000000b003da63711a8aso7785429edj.20 for ; Fri, 12 Nov 2021 02:09:32 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=GpT2YYqG29Jg+Uxsx2CrH+IJrT+DNnW+q/s5xR+/nO8=; b=nPayDeUZHABfmL2YsXUHryv4GKQE+fk+n7Q/plNDJP6wWzF1xwphJ4DpvJAZr7HdeH SVQpvn7s3zTax8oRe4rnSo+4uwkOIIGyJwppGqckWqD22rDY8Rw5F3GoORyq00rpEPJ4 G5rczk8TflOzd+Du+xEOqv1lvFgZi1Z4dApnyU7vZO1mtGujJwTVjSyuX8UOMGM5xdzB TBECVLGUzvS+VixfgiZQvIEhYcNsfns8hx/MnO0v/4eaA8n7Kdx70Crqah1AsbIs9V9q RTAO3a7k3vl98LI899UApe9P4koZMtPKpgfdAtmB6mFSqAuNEXwb+nVIlcqji3rVCeTR yxpA== X-Gm-Message-State: AOAM533i3tat6R9GU66jrd8mqBX8mYcwBP2i0fV5uYYw+THIxmBqUec8 ZQpIxdyUNEUVvc17OuGVkfM6NCWVbsiLB2pbO/uogRt3/PEGHU9B2jDGnecRyVzMPYbfDoPAw15 ifTX2twRTyCisnOZQCQC0oRiz X-Received: by 2002:a17:907:869e:: with SMTP id qa30mr17383098ejc.356.1636711772008; Fri, 12 Nov 2021 02:09:32 -0800 (PST) X-Google-Smtp-Source: ABdhPJwIZCg8KaRPHh5tzSrNXTPjAyfDOZFhQ7POM6eHpQhHd+dmXCDKysUay1ewM1e6Mb40QOB2uQ== X-Received: by 2002:a17:907:869e:: with SMTP id qa30mr17383074ejc.356.1636711771835; Fri, 12 Nov 2021 02:09:31 -0800 (PST) Received: from redhat.com ([2a03:c5c0:207e:ac28:448d:9310:293c:3a8b]) by smtp.gmail.com with ESMTPSA id ho30sm2409248ejc.30.2021.11.12.02.09.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 12 Nov 2021 02:09:31 -0800 (PST) Date: Fri, 12 Nov 2021 05:09:27 -0500 From: "Michael S. Tsirkin" To: Gerd Hoffmann Cc: linux-pci@vger.kernel.org, Bjorn Helgaas , open list Subject: Re: [PATCH] pciehp: fast unplug for virtual machines Message-ID: <20211112050508-mutt-send-email-mst@kernel.org> References: <20211111090225.946381-1-kraxel@redhat.com> <20211111115931-mutt-send-email-mst@kernel.org> <20211112095629.uoxfuhsvhicsdxgd@sirius.home.kraxel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20211112095629.uoxfuhsvhicsdxgd@sirius.home.kraxel.org> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Nov 12, 2021 at 10:56:29AM +0100, Gerd Hoffmann wrote: > Hi, > > > > This patch adds the fast_virtual_unplug module parameter to the > > > pciehp driver. When enabled (which is the default) the linux > > > kernel will simply skip the delay for virtual pcie ports, which > > > reduces the total time for the unplug operation from 6-7 seconds > > > to 1-2 seconds. > > > > BTW how come it's still taking seconds, not milliseconds? > > I've tackled the 5 seconds only, biggest chunk and easy target because > the only reason to have that is to allow operators press the attention > button again to cancel, so the risk to break something here is rather > low. > > There are some more wait times elsewhere, to give the hardware the > time needed when powering up/down slots, which sum up to roughly one > second, and the time the driver needs to shutdown the device goes on > top of that (typically not much). > > take care, > Gerd Probably also unnecessary for a virtual bridge. We'll need to fix these up if we want native hotplug to be useful for workloads like kata - these expect hotplug time in the milliseconds. -- MST