On 03.03.2020 13:10, Gerd Hoffmann wrote:
On Tue, Mar 03, 2020 at 12:28:32PM +0100, Anton Yakovlev wrote:
Hi,
On 03.03.2020 12:20, Gerd Hoffmann wrote:
Hi,
4. Introduce the polling mode feature for a message-based transport.
BTW: is that driver -> device or device -> driver or both?
In case both: should we have two separate feature flags maybe?
It's driver -> device direction. The driver needs notifications from the
device in any case, so it makes no sense to suppress notifications in this
direction (device -> driver).
Hmm, unless I missed something it doesn't matter whenever the guest
kernel checks virtqueues from irq handler or timer ...
Because in the general case, it is impossible to predict when a notification
will come from the device. Even if we are talking about a period time, this
does not mean that the device will send notifications precisely at these
intervals. And this means that the driver must do a tricky poll, trying
to guess when the notification will arrive, i.e. just waste CPU resources.
cheers,
Gerd
--
Anton Yakovlev
Senior Software Engineer
OpenSynergy GmbH
Rotherstr. 20, 10245 Berlin
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