Re: perf: Support uncore in 4.9.112

[Greg KH <gregkh@linuxfoundation.org>]

On Wed, Aug 08, 2018 at 08:58:01AM +0800, Jin, Yao wrote:
> 
> 
> On 8/7/2018 9:09 PM, Greg KH wrote:
> > 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...
> > 
> 
> Hi Greg,
> 
> Ali needs the uncore patches and they have backported to their tree. So for
> adding uncore patches to stable tree, just neutral for them.
> 
> I wish to show that 4.9 is being used by some customers.
> 
> > And why did no one answer all of my questions from my first email?
> > 
> 
> Sorry about that. I just answer part of questions, for example, "The
> patchset supports the server like Skylake, and it also supports some old
> servers, for example, Broadwell and Haswell, .....". I want to represent
> that it's not only for new hardware like SKL but also for some old hardware
> which may run with 4.9.
> 
> But for other questions, such as, who uses 4.9 in desktop, what distros need
> 4.9. I'm sorry I don't really know the answers so I don't reply. Sorry about
> that.

I asked for the diffstat :(