netdev - Re: EEVDF/vhost regression (bisected to 86bfbb7ce4f6 sched/fair: Add lag based placement)

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <4808eab5fc5c85f12fe7d923de697a78@linux.ibm.com>
Date: Tue, 19 Mar 2024 09:59:30 +0100
From: Tobias Huschle <huschle@...ux.ibm.com>
To: "Michael S. Tsirkin" <mst@...hat.com>
Cc: Luis Machado <luis.machado@....com>, Jason Wang <jasowang@...hat.com>,
        Abel Wu <wuyun.abel@...edance.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Linux Kernel <linux-kernel@...r.kernel.org>, kvm@...r.kernel.org,
        virtualization@...ts.linux.dev, netdev@...r.kernel.org,
        nd <nd@....com>
Subject: Re: EEVDF/vhost regression (bisected to 86bfbb7ce4f6 sched/fair: Add
 lag based placement)

On 2024-03-19 09:29, Michael S. Tsirkin wrote:
> On Tue, Mar 19, 2024 at 09:21:06AM +0100, Tobias Huschle wrote:
>> On 2024-03-15 11:31, Michael S. Tsirkin wrote:
>> > On Fri, Mar 15, 2024 at 09:33:49AM +0100, Tobias Huschle wrote:
>> > > On Thu, Mar 14, 2024 at 11:09:25AM -0400, Michael S. Tsirkin wrote:
>> > > >
>> >
>> > Could you remind me pls, what is the kworker doing specifically that
>> > vhost is relying on?
>> 
>> The kworker is handling the actual data moving in memory if I'm not
>> mistaking.
> 
> I think that is the vhost process itself. Maybe you mean the
> guest thread versus the vhost thread then?

My understanding was that vhost writes data into a file descriptor which 
then triggers eventfd.

That's at least how I read the vhost code if I remember correctly.

The handler beneath (the kworker) then runs the actual instructions that 
move the data to the receiving vhost on the other end of the connection.

Again, I might be wrong here.