From: "Michael S. Tsirkin" <mst@redhat.com>
To: Gerd Hoffmann <kraxel@redhat.com>
Cc: linux-pci@vger.kernel.org, Bjorn Helgaas <bhelgaas@google.com>,
open list <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] pciehp: fast unplug for virtual machines
Date: Fri, 12 Nov 2021 05:09:27 -0500 [thread overview]
Message-ID: <20211112050508-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <20211112095629.uoxfuhsvhicsdxgd@sirius.home.kraxel.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
next prev parent reply other threads:[~2021-11-12 10:09 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-11 9:02 [PATCH] pciehp: fast unplug for virtual machines Gerd Hoffmann
2021-11-11 17:00 ` Michael S. Tsirkin
2021-11-12 9:56 ` Gerd Hoffmann
2021-11-12 10:09 ` Michael S. Tsirkin [this message]
2021-11-11 21:50 ` Bjorn Helgaas
2021-11-12 11:28 ` Gerd Hoffmann
2021-11-12 0:00 ` Krzysztof Wilczyński
2021-11-14 16:39 ` Lukas Wunner
2021-11-14 17:24 ` Michael S. Tsirkin
2021-11-14 18:06 ` Lukas Wunner
2021-11-14 22:37 ` Michael S. Tsirkin
2021-11-15 9:59 ` Gerd Hoffmann
2021-11-15 7:45 ` Lukas Wunner
2021-11-15 10:09 ` Gerd Hoffmann
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20211112050508-mutt-send-email-mst@kernel.org \
--to=mst@redhat.com \
--cc=bhelgaas@google.com \
--cc=kraxel@redhat.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-pci@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).