linux-kernel - Re: [PATCH V2 0/3] basic busy polling support for vhost

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Message-ID: <loom.20160124T095157-151@post.gmane.org>
Date:	Sun, 24 Jan 2016 09:00:01 +0000 (UTC)
From:	Mike Rapoport <rapoport@...ibm.com>
To:	linux-kernel@...r.kernel.org
Subject: Re: [PATCH V2 0/3] basic busy polling support for vhost_net

Hi Jason,

> Jason Wang <jasowang <at> redhat.com> writes:
> 
> Hi all:
> 
> This series tries to add basic busy polling for vhost net. The idea is
> simple: at the end of tx/rx processing, busy polling for new tx added
> descriptor and rx receive socket for a while.

There were several conciens Michael raised on the Razya's attempt to add
polling to vhost-net ([1], [2]). Some of them seem relevant for these
patches as well:

- What happens in overcommit scenarios?
- Have you checked the effect of polling on some macro benchmarks?

> The maximum number of time (in us) could be spent on busy polling was
> specified ioctl.

Although ioctl is definitely more appropriate interface to allow user to
tune polling, it's still not clear for me how *end user* will interact with
it and how easy it would be for him/her.

[1] http://thread.gmane.org/gmane.linux.kernel/1765593
[2] http://thread.gmane.org/gmane.comp.emulators.kvm.devel/131343

--
Sincerely yours,
Mike.