Re: perf: Support uncore in 4.9.112

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On Mon, Aug 06, 2018 at 08:46:32AM +0800, Jin, Yao wrote:
> 
> 
> On 7/19/2018 1:39 AM, Greg KH wrote:
> > On Wed, Jul 18, 2018 at 10:09:44AM -0700, Andi Kleen wrote:
> > > On Wed, Jul 18, 2018 at 11:29:50AM +0200, Greg KH wrote:
> > > > On Wed, Jul 18, 2018 at 08:41:28AM +0800, Jin, Yao wrote:
> > > > > Hi,
> > > > > 
> > > > > The stable kernel 4.9.112 has supported Intel uncore feature in perf core.
> > > > > While it also needs the perf tool supporting to let perf uncore feature
> > > > > work.
> > > > > 
> > > > > Following backport patches enables basic perf uncore feature in 4.9.112.
> > > > > 
> > > > > For example, on skylake desktop,
> > > > 
> > > > Why would anyone care about this on a "desktop" for 4.9?  No one should
> > > > be using 4.9.y on a desktop anymore, it's over 2 years old, why would
> > > > they expect any "new" hardware support to work for them?  Why can't they
> > > 
> > > It's actually not new hardware support: Skylake is fairly old hardware
> > > at this point.
> > 
> > So is 4.9.  I don't understand your point.  The hardware is obviously
> > newer than 4.9 was, otherwise the support for it would already be in
> > there, right?
> > 
> > > > just use 4.14.y or better yet. 4.17.y?  Desktops should NOT be using a 2
> > > > year old kernel.
> > > > 
> > > > Heck, servers shouldn't either, but that's a totally different rant.
> > > 
> > > These chips are not only used in desktops but also in servers.
> > 
> > This was asked for with regards to desktops, so now I'm confused.
> > Exactly who/what is going to be needing/wanting/using these changes?
> > 
> > > > However, for hardware that is newer than the base kernel version
> > > > release, I have no sympathy.  Just use a newer kernel, right?
> > > 
> > > We have customers which are on old kernels with new hardware.
> > 
> > That's obviously not a wise thing to do for lots of good reasons.  This
> > exact example being a huge one (i.e. you can't go back in time and add
> > support for hardware that was not out yet.)
> > 
> > > The backports happen either way. This is just an attempt to do it in a
> > > coordinated fashion.
> > 
> > There was no coordination here, just a list of git commit ids.  Which is
> > great, and all that is really needed, but I'm confused as to who is
> > trying to coordinate with who?
> > 
> > > > What distro relies on a 4.9 kernel for brand new hardware that does not
> > > > already support a newer kernel release for such hardware?
> > > 
> > > None afaik, but there is a lot of Linux use beyond distros.
> > 
> > So no distro uses this, which makes me really wonder who would be the
> > user of these backports.  And for how long?  Why are these people not
> > moving to 4.14 already given that the published date for 4.9 end-of-life
> > is getting very close.  Are you expecting to be rescued by Google again?
> > 
> 
> Hi Greg,
> 
> We do see 4.9 is now used by Alibaba.
> 
> Ali kernel is opensourced at https://github.com/alibaba/alikernel

Ok, does this user require these patches?  Do they have them in their
kernel already?  Do they need me to add them before they can use the
hardware they already have?  I don't understand the connection here...

And why did no one answer all of my questions from my first email?

greg k-h



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