From: Tobias Huschle <huschle@linux.ibm.com>
To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
Luis Machado <luis.machado@arm.com>,
Jason Wang <jasowang@redhat.com>,
Abel Wu <wuyun.abel@bytedance.com>,
Linux Kernel <linux-kernel@vger.kernel.org>,
kvm@vger.kernel.org, virtualization@lists.linux.dev,
netdev@vger.kernel.org, nd <nd@arm.com>,
borntraeger@linux.ibm.com, Ingo Molnar <mingo@kernel.org>,
Mike Galbraith <umgwanakikbuti@gmail.com>
Subject: Re: EEVDF/vhost regression (bisected to 86bfbb7ce4f6 sched/fair: Add lag based placement)
Date: Thu, 2 May 2024 14:23:33 +0200 [thread overview]
Message-ID: <ZjOFxbsHuQZ+Zltu@DESKTOP-2CCOB1S.> (raw)
In-Reply-To: <20240501112830-mutt-send-email-mst@kernel.org>
On Wed, May 01, 2024 at 11:31:02AM -0400, Michael S. Tsirkin wrote:
> On Wed, May 01, 2024 at 12:51:51PM +0200, Peter Zijlstra wrote:
> > On Tue, Apr 30, 2024 at 12:50:05PM +0200, Tobias Huschle wrote:
<...>
> >
> > I'm still wondering why exactly it is imperative for t2 to preempt t1.
> > Is there some unexpressed serialization / spin-waiting ?
>
>
> I am not sure but I think the point is that t2 is a kworker. It is
> much cheaper to run it right now when we are already in the kernel
> than return to userspace, let it run for a bit then interrupt it
> and then run t2.
> Right, Tobias?
>
That would be correct, the optimal scenario would be that t1, the vhost
does its thing, wakes up t2, the kworker, makes sure t2 executes immediately,
then gets control again and continues watching its loops without ever
leaving kernel space.
next prev parent reply other threads:[~2024-05-02 12:23 UTC|newest]
Thread overview: 58+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-11-16 18:58 EEVDF/vhost regression (bisected to 86bfbb7ce4f6 sched/fair: Add lag based placement) Tobias Huschle
2023-11-17 9:23 ` Peter Zijlstra
2023-11-17 9:58 ` Peter Zijlstra
2023-11-17 12:24 ` Tobias Huschle
2023-11-17 12:37 ` Peter Zijlstra
2023-11-17 13:07 ` Abel Wu
2023-11-21 13:17 ` Tobias Huschle
2023-11-22 10:00 ` Peter Zijlstra
2023-11-27 13:56 ` Tobias Huschle
[not found] ` <6564a012.c80a0220.adb78.f0e4SMTPIN_ADDED_BROKEN@mx.google.com>
2023-11-28 8:55 ` Abel Wu
2023-11-29 6:31 ` Tobias Huschle
2023-12-07 6:22 ` Tobias Huschle
[not found] ` <07513.123120701265800278@us-mta-474.us.mimecast.lan>
2023-12-07 6:48 ` Michael S. Tsirkin
2023-12-08 9:24 ` Tobias Huschle
2023-12-08 17:28 ` Mike Christie
[not found] ` <56082.123120804242300177@us-mta-137.us.mimecast.lan>
2023-12-08 10:31 ` Re: " Michael S. Tsirkin
2023-12-08 11:41 ` Tobias Huschle
[not found] ` <53044.123120806415900549@us-mta-342.us.mimecast.lan>
2023-12-09 10:42 ` Michael S. Tsirkin
2023-12-11 7:26 ` Jason Wang
2023-12-11 16:53 ` Michael S. Tsirkin
2023-12-12 3:00 ` Jason Wang
2023-12-12 16:15 ` Michael S. Tsirkin
2023-12-13 10:37 ` Tobias Huschle
[not found] ` <42870.123121305373200110@us-mta-641.us.mimecast.lan>
2023-12-13 12:00 ` Michael S. Tsirkin
2023-12-13 12:45 ` Tobias Huschle
[not found] ` <25485.123121307454100283@us-mta-18.us.mimecast.lan>
2023-12-13 14:47 ` Michael S. Tsirkin
2023-12-13 14:55 ` Michael S. Tsirkin
2023-12-14 7:14 ` Michael S. Tsirkin
2024-01-08 13:13 ` Tobias Huschle
[not found] ` <92916.124010808133201076@us-mta-622.us.mimecast.lan>
2024-01-09 23:07 ` Michael S. Tsirkin
2024-01-21 18:44 ` Michael S. Tsirkin
2024-01-22 11:29 ` Tobias Huschle
2024-02-01 7:38 ` Tobias Huschle
[not found] ` <07974.124020102385100135@us-mta-501.us.mimecast.lan>
2024-02-01 8:08 ` Michael S. Tsirkin
2024-02-01 11:47 ` Tobias Huschle
[not found] ` <89460.124020106474400877@us-mta-475.us.mimecast.lan>
2024-02-01 12:08 ` Michael S. Tsirkin
2024-02-22 19:23 ` Michael S. Tsirkin
2024-03-11 17:05 ` Michael S. Tsirkin
2024-03-12 9:45 ` Luis Machado
2024-03-14 11:46 ` Tobias Huschle
[not found] ` <73123.124031407552500165@us-mta-156.us.mimecast.lan>
2024-03-14 15:09 ` Michael S. Tsirkin
2024-03-15 8:33 ` Tobias Huschle
[not found] ` <84704.124031504335801509@us-mta-515.us.mimecast.lan>
2024-03-15 10:31 ` Michael S. Tsirkin
2024-03-19 8:21 ` Tobias Huschle
2024-03-19 8:29 ` Michael S. Tsirkin
2024-03-19 8:59 ` Tobias Huschle
2024-04-30 10:50 ` Tobias Huschle
2024-05-01 10:51 ` Peter Zijlstra
2024-05-01 15:31 ` Michael S. Tsirkin
2024-05-02 9:16 ` Peter Zijlstra
2024-05-02 12:23 ` Tobias Huschle [this message]
2024-05-02 12:20 ` Tobias Huschle
2023-11-18 5:14 ` Abel Wu
2023-11-20 10:56 ` Peter Zijlstra
2023-11-20 12:06 ` Abel Wu
2023-11-18 7:33 ` Abel Wu
2023-11-18 15:29 ` Honglei Wang
2023-11-19 13:29 ` Bagas Sanjaya
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