Gentoo Archives: gentoo-dev

From: "C Bergström" <cbergstrom@×××××××××.com>
To: "Anthony G. Basile" <gentoo-dev@l.g.o>
Subject: Re: [gentoo-dev] New project: LLVM
Date: Fri, 19 Aug 2016 21:05:32
In Reply to: Re: [gentoo-dev] New project: LLVM by james
1 On Sat, Aug 20, 2016 at 4:52 AM, james <garftd@×××××××.net> wrote:
3 <snip>
5 >> Back to my own glass house.. It will take a few years, but I am trying
6 >> to make it easier (internally) to expose in some clear way all the
7 >> pieces which compose a fine tuning per-processor. If this was "just"
8 >> scheduling models it would be really easy, but it's not.. Those
9 >> latencies and other magic bits decide things like.. "should I unroll
10 >> this loop or do something else" and then you venture into the land of
11 >> accelerators where a custom regalloc may be what you really need and
12 >> *nothing* off the shelf fits to meet your goals.. (projects like that
13 >> can take 9 months and in the end only give a general 1-5% median
14 >> performance gain..)
15 >
16 >
17 > If this is your mantra, I resend the generous comments. Cray use to work
18 > that way, milking the Petroleum Industry for tons of money, but, things have
19 > changed and the change is accelerating, rapidly. Perhaps too much off those
20 > Cray patents that your company owns are leaking toxins into the brain-trust
21 > where you park?
22 >
23 > Vendor walk-back is sad, imho. ymmv.
24 >
25 > Best of luck to your company's 5-year plan....
27 I have no idea what on earth you were trying to say in most of your
28 reply. I am speaking only from a compiler perspective. Nothing more
29 and nothing less.. it may be my difficultly to describe the target
30 level and processor specific optimization choices a compiler *must*
31 make.
33 Beyond not understanding your email, I found it insulting. So please
34 keep rude comments to yourself.
36 So again to try to explain the technical side of this - We can't and
37 have no desire to optimize for every class of processor on the planet.
38 We have a narrow band of focus on mostly HPC centric code patterns and
39 processors which are are typically used in HPC workloads. I'd love to
40 expand past this, but we're a small company and that's our niche.
41 There's no walking back or trying to claim to be something we're not..
42 this is pure honest transparency. (imagine it like - do one thing and
43 do it well)
45 The only special note I'd add on to this - the CPU isn't where we
46 spend most of our time tuning, it's by far more on the accelerator
47 support.


Subject Author
Re: [gentoo-dev] New project: LLVM james <garftd@×××××××.net>