On Thu, Mar 8, 2012 at 3:27 PM, Ben Pfaff <[email protected]> wrote:
> On Thu, Mar 08, 2012 at 03:25:16PM -0800, Pravin Shelar wrote:
>> On Thu, Mar 8, 2012 at 3:15 PM, Ben Pfaff <[email protected]> wrote:
>> > On Thu, Mar 08, 2012 at 03:07:41PM -0800, Pravin Shelar wrote:
>> >> On Thu, Mar 8, 2012 at 2:57 PM, Ben Pfaff <[email protected]> wrote:
>> >> > On Thu, Mar 08, 2012 at 07:26:08AM -0800, Pravin B Shelar wrote:
>> >> >> Fixed according to comments from Ben.
>> >> >> v1-v2:
>> >> >> - Added comment for netdev_internal_open
>> >> >> - Removed get-stat call from status check.
>> >> >>
>> >> >> --8<--------------------------cut here-------------------------->8--
>> >> >>
>> >> >> Netdev-linux calls ETHTOOL_GDRVINFO on every netdev_linux_get_status()
>> >> >> which is not optimal as drv-info does not change for given device.
>> >> >> So following patch changes netdev_linux_get_status() to read drv-info
>> >> >> at
>> >> >> device initialization and cache it.
>> >> >>
>> >> >> Signed-off-by: Pravin B Shelar <[email protected]>
>> >> >
>> >> > Thanks.
>> >> >
>> >> > This series has a number of patches with the similar purposes of
>> >> > increasing the effectiveness of caching in netdev-linux. They tend to
>> >> > follow the same pattern. But this patch stands out as the only one
>> >> > that populates the cache proactively, before the client asks for it.
>> >> > Why is drvinfo different? That is, if we have to populate drvinfo
>> >> > proactively, why don't we have to populate the other values
>> >> > proactively too?
>> >>
>> >> I didn't do it as we always cache drv-info info. If you want I can add
>> >> caching for error code.
>> >
>> > I mean, this patch obtains the drvinfo as soon as possible, either in
>> > the "open" call (for non-internal netdevs) or as soon as we get an
>> > rtnetlink notification that the device was created (for internal
>> > netdevs). For, say, MTU, we don't do that. Instead, we wait for the
>> > client to ask for the MTU the first time, and then netdev-linux
>> > obtains the MTU and caches it[*]. That seems like a sensible way to
>> > do things; in particular it makes "open" cheap. Is there some reason
>> > that we can do that for MTU but not for drvinfo?
>>
>> I did it for drv-info as it might not be available later when it is
>> asked for; in case device is unregistered.
>
> Why is that true for drvinfo but not for, say, MTU?
as MTU can change and cache will get discarded by dev unregister notification.
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