Re: [Qemu-devel] qemu-user-linux: how could I measure performance for aarch64 and arm?

[Matwey V. Kornilov]

пн, 14 янв. 2019 г. в 13:24, Peter Maydell <address@hidden>:
>
> On Sun, 13 Jan 2019 at 07:31, Matwey V. Kornilov
> <address@hidden> wrote:
> >
> > пт, 11 янв. 2019 г. в 22:24, Matwey V. Kornilov <address@hidden>:
> > > Indeed, qemu-arm from master runs for 4 minutes where 2.11 runs for 2
> > > hours for me. It is impressive improvement.
> >
> > I've managed to bisected the first good (fast) commit:
> >
> > commit 2a53535af471f4bee9d6cb5b363746b8d5ed21dd
> > Author: Luke Shumaker <address@hidden>
> > Date:   Thu Dec 28 13:08:13 2017 -0500
> >
> >     linux-user: init_guest_space: Try to make ARM space+commpage continuous
> >
> > Though I am not sure, how does it help.
>
> Oh, right, you were running into that bug:
> https://bugs.launchpad.net/qemu/+bug/1740219
>
> The problem was that we were not putting things in the right
> place in memory for 32-bit Arm guest binaries in particular,
> which could mean that we spent a long time trying a lot of
> placements for memory mappings that failed instead of getting
> an arrangement that worked first time. This meant startup
> time for the guest binary was pretty slow. I guess your
> application does a lot of exec()ing of new processes?

Indeed. Thank you.

>
> thanks
> -- PMM



-- 
With best regards,
Matwey V. Kornilov