From: "Michael S. Tsirkin" <mst@redhat.com>
To: Seth Forshee <seth.forshee@canonical.com>
Cc: Jason Wang <jasowang@redhat.com>,
virtualization@lists.linux-foundation.org,
netdev@vger.kernel.org
Subject: Re: Performance regression with virtio_net
Date: Thu, 27 Jul 2017 23:38:52 +0300 [thread overview]
Message-ID: <20170727233244-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <20170727170942.ub24lwgrl3x2outp@ubuntu-hedt>
On Thu, Jul 27, 2017 at 12:09:42PM -0500, Seth Forshee wrote:
> I'm seeing a performance regression with virtio_net that looks to have
> started in 4.12-rc1. I only see it in one context though, downloading
> snap packages from the Ubuntu snap store. For example:
>
> https://api.snapcraft.io/api/v1/snaps/download/b8X2psL1ryVrPt5WEmpYiqfr5emixTd7_1797.snap
>
> which redirects to Internap's CDN. Normally this downloads in a few
> seconds at ~10 MB/s, but with 4.12 and 4.13 it takes minutes with a rate
> of ~150 KB/s. Everything else I've tried downloads as normal speeds.
So just wget that URL should be enough?
> I bisected this to 680557cf79f8 "virtio_net: rework mergeable buffer
> handling". If I revert this on top of 4.13-rc2 (along with other changes
> needed to successfully revert it) speeds return to normal.
>
> Thanks,
> Seth
Interesting. A more likely suspect would be
e377fcc8486d40867c6c217077ad0fa40977e060 - could you please try
reverting that one instead?
Also, could you please look at mergeable_rx_buffer_size in sysfs with
and without the change?
--
MST
next prev parent reply other threads:[~2017-07-27 20:38 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-07-27 17:09 Performance regression with virtio_net Seth Forshee
2017-07-27 20:38 ` Michael S. Tsirkin [this message]
2017-07-27 21:14 ` Seth Forshee
2017-07-27 21:30 ` Michael S. Tsirkin
2017-07-28 13:12 ` Seth Forshee
-- strict thread matches above, loose matches on Subject: below --
2017-07-30 22:25 Euan Kemp
2017-07-31 13:26 ` Michael S. Tsirkin
2017-07-31 14:29 ` Seth Forshee
2017-07-31 18:38 ` Euan Kemp
2017-07-31 18:50 ` Michael S. Tsirkin
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