Well, this settles it for me
Well, this settles it for me
Posted Sep 7, 2009 6:47 UTC (Mon) by bvdm (guest, #42755)Parent article: BFS vs. mainline scheduler benchmarks and measurements
Did Ingo respond in an unreasonable way? No, he his email was nothing but courteous, though written by someone who is evidently confident of his case.
Are Ingo's benchmarks unreasonable? No, only a fool would consider well-chosen benchmarks as completely worthless. Ingo did not attack BFS's use cases, only made a case for the mainline ones.
The bottom line is that Ingo made it clear that his concern is the mainline scheduler. He could have picked arbitrary benchmarks and run them on a netbook if he wanted to embarrass Con.
If you can't stand the heat, why go back into the kitchen?
Posted Sep 7, 2009 7:22 UTC (Mon)
by yoshi314 (guest, #36190)
[Link] (22 responses)
benchmarks he did are relevant to more high-end machines.
con has a point, both about the choice of hardware and selection of
but his attitude is awful. this might serve as a starting point for re-
Posted Sep 7, 2009 7:32 UTC (Mon)
by bvdm (guest, #42755)
[Link] (11 responses)
Secondly, one hardly wants to re-implement something like a scheduler every year. Designing for the near and medium future creates stability. Anyway, you would be hard pressed to find a desktop machine without at least 2 cores these days.
As for netbooks, if interactivity (people keep posting about gaming FPS and high-def audio and high-res desktop experience) is such a concern, why are you using a netbook? A typical netbook has far fewer processes running.
I don't think there ever was a "war". It is a shame that so much unproductive drama was generated by someone who is evidently skillful at performing for the peanut gallery.
Posted Sep 7, 2009 7:44 UTC (Mon)
by k8to (guest, #15413)
[Link] (3 responses)
Yes, this is subjective and I'm sure it has noise. I think it's also the truth.
Posted Sep 7, 2009 7:45 UTC (Mon)
by k8to (guest, #15413)
[Link]
Posted Sep 7, 2009 8:03 UTC (Mon)
by bvdm (guest, #42755)
[Link] (1 responses)
But seriously, the only objective measures we have are the number of contributors and SLOC added, and both of these are still accelerating.
Now I would be astounded if the Linux kernel were the only technical project in the world without non-technical problems, but don't you think there are many other explanations for this change in perception? Such as, perhaps:
- That having your code included in the kernel has a much increased monetary benefit and is therefore more sought after
And are the driver staging tree and desktop and security advances such as KMS and SMACK not countersigns to what you are suggesting?
Posted Sep 7, 2009 18:24 UTC (Mon)
by k8to (guest, #15413)
[Link]
It's likely to be driven by standards, but the contention is that these standards are often more arbitrary than useful.
Ego on the part of the maintainers is certainly involved. Among my contacts, ego on the part of the author has certain not *risen* in the interim, although it may be high (I doubt it).
Stability has certainly become more prized.
Posted Sep 7, 2009 16:06 UTC (Mon)
by einstein (guest, #2052)
[Link] (1 responses)
I don't think that we desktop linux users are entirely happy with smug little comments like that. For us, linux is the only desktop presence and it looms large.
> so not entirely optimizing for the desktop is a rational design decision, though "totally disconnected" is very hard to swallow.
I think Con may have a valid point in questioning the one-size fits all paradigm. While it's an admirable goal to create a single kernel which runs optimally on everything from PDAs to supercomputing clusters, there may be too much of a divergence in performance profiles for that to be entirely practical.
As Linus has said, a desktop linux presence is vital to its viability, so optimizing desktop interactivity ought to be a very high priority.
Posted Sep 7, 2009 22:24 UTC (Mon)
by mingo (guest, #31122)
[Link]
As Linus has said, a desktop linux presence is vital to its viability, so optimizing desktop interactivity ought to be a very high priority.
It is. See for example this recent discussion on lkml. That discussion and those (non-trivial) patches were all about desktop latencies - and it's all part of v2.6.30 now.
Posted Sep 7, 2009 22:20 UTC (Mon)
by man_ls (guest, #15091)
[Link] (4 responses)
Posted Sep 9, 2009 7:57 UTC (Wed)
by gmaxwell (guest, #30048)
[Link] (3 responses)
Meanwhile I do audio processing with a ~2ms processing interval using the mainline scheduler, thrashing the system, high loads... and underruns are basically unheard of at least after tossing the drivers and hardware that I determined were misbehaving (with measurements, ... imagine that!)
I don't doubt that there are genuine areas for improvement, even in the scheduler but it isn't going to get better without real measurements and some social skills superior to those of Hans Reiser.
Posted Sep 9, 2009 20:14 UTC (Wed)
by man_ls (guest, #15091)
[Link] (2 responses)
As to the benchmarks, the first test was how fast can he build the kernel using n processes. Well, this is only measuring thoughput; if each process is supposed to be interactive, it is not unreasonable to expect that they will more easily interrupted and thus the build will last longer. Then a very artificial pipe-messaging test, followed by similarly contrived benchmarks -- which CFS has already been tuned to. So the "other side" (lkml) has not been able to produce anything better either to show that CFS is good at interactivity, measuring skips and jitter, and I find this to be even more pitiful.
Posted Sep 9, 2009 23:40 UTC (Wed)
by njs (subscriber, #40338)
[Link] (1 responses)
To be fair, that benchmark is originally Con's, not Ingo's (Con's original announcement claims that "make -j4 on a quad core machine with BFS is faster than *any* choice of job numbers on CFS").
Posted Sep 10, 2009 9:52 UTC (Thu)
by man_ls (guest, #15091)
[Link]
Posted Sep 7, 2009 7:46 UTC (Mon)
by andreashappe (subscriber, #4810)
[Link] (9 responses)
> i've been getting the impression recently that core kernel devs are totally
I've bought a new desktop rig three months ago and paid not unreasonable 1100 euro for a quad core (+hyper-threading) i7 processor backed up by 6gb ram.
I do not believe that Linux should target < 1000 Euro machines (at least not for mainline development). If there's use for another scheduler Con can keep it out-of-tree (as he seems to intend to). When distributions pick it up it might even get into mainline. But his childish behaviour after Ingo benchmarked his patch (with a workload that was well within the Con's use case description) does not bode well. Not well at all.
cheers, Andreas
Posted Sep 7, 2009 8:03 UTC (Mon)
by Cato (guest, #7643)
[Link] (4 responses)
Posted Sep 7, 2009 8:11 UTC (Mon)
by andreashappe (subscriber, #4810)
[Link] (3 responses)
I was talking about _mainline_. Pray read the rest of my post (where I mentined out-of-tree patches). And AFAIK embedded systems often have out-of-tree patchsets for their architectures.
> The majority of laptops and desktops these days cost less than 1000 Euros/USD
If some scheduler thing would be added to the kernel this would take 2-3 release cycles (at least).. by which time multi-core systems are even more common than today.
cheers, Andreas
Posted Sep 7, 2009 15:45 UTC (Mon)
by broonie (subscriber, #7078)
[Link] (2 responses)
Posted Sep 7, 2009 16:01 UTC (Mon)
by andreashappe (subscriber, #4810)
[Link] (1 responses)
cheers, Andreas
Posted Sep 7, 2009 16:25 UTC (Mon)
by broonie (subscriber, #7078)
[Link]
Posted Sep 7, 2009 8:30 UTC (Mon)
by sitaram (guest, #5959)
[Link]
You will not believe the number of people in India who still use P4s (and God even P3s sometimes). Far more than the Core2Duo kind, I rather suspect. Maybe not in new purchases but in total numbers. We don't throw away stuff so fast anyway.
After reading your email I'm even more convinced that Ingo did not understand what Con was trying to say (*)
Sitaram
(*) ...or he did but didn't want to risk saying the sort of stuff you said ;-)
Posted Sep 7, 2009 9:13 UTC (Mon)
by endecotp (guest, #36428)
[Link] (2 responses)
Maybe you're living on a different planet. The only time I've ever spent anything like that much was my first PC back in 1994 - a 66MHz 486.
Posted Sep 7, 2009 12:46 UTC (Mon)
by pboddie (guest, #50784)
[Link]
Posted Sep 7, 2009 16:07 UTC (Mon)
by andreashappe (subscriber, #4810)
[Link]
Could be, I'm using it for coding and running statistics stuff mostly (while doing 'normal' video/music listening).
But that thing did cost me around 1000 euro four months ago and would be under that by now.. and will be fairly standard *before* a new scheduler would be added to mainline.
People that experiencing performance or latency problems on existing hardware might be better of if they would just *report* their problems to the lkml. Ingo is quite responsive to feedback.
(embedded usage differs.. but that is something that the market (tm) should be perfectly able to decide).
Posted Sep 7, 2009 11:24 UTC (Mon)
by rsidd (subscriber, #2582)
[Link] (4 responses)
If you can't stand the heat, why go back into the kitchen?
Con did not go back into the kitchen. He was explicitly avoiding LKML. Ingo tried to pull him in. And posting graphs as 6001x4201 JPG files shows extraordinary cluelessness. Every graphing program I've seen supports vector formats like EPS or PDF, and if he must use JPG, he can at least choose a size that fits on screen -- or does he use a 6000x4200 resolution monitor?
I'm running a Core 2 duo laptop with 4 GB RAM, and most of the time I don't suffer interactivity issues. But on lesser machines it is a big problem. If Ingo doesn't use such machines, he should be quiet. Con's problem was not "performance", it was interactivity, and Ingo's benchmarks are basically beside the point.
Jens Axboe posted other benchmarks that sound more reasonable as measures of interactivity (which is Con's concern, not "performance"), and he is not happy with CFS, but he was not able to boot the BFS kernel.
Posted Sep 7, 2009 11:38 UTC (Mon)
by bvdm (guest, #42755)
[Link] (1 responses)
Your comments about the image size ares just ad hominem which I will ignore.
Have you read Ignor's email carefully or at all? He is clearly making the case that, whatever BFS's advantages on lower end machines may be (which he chose not to contest), CFS is still better suited for the mainline.
No-one is arguing that CFS is perfect, but I have a grave concern that Con is *again* pissing in the drinking well with his style of doing things.
Posted Sep 7, 2009 22:35 UTC (Mon)
by man_ls (guest, #15091)
[Link]
Posted Sep 7, 2009 13:05 UTC (Mon)
by aigarius (subscriber, #7329)
[Link]
Posted Sep 9, 2009 11:27 UTC (Wed)
by liljencrantz (guest, #28458)
[Link]
I agree that Ingos choice of test machine and benchmarks is telling when it comes to what his priorities are - he gets paid to create software that runs well on big systems, 8 CPUs probably looks small to him. No malice or stupidity involved, just a different perspective.
I think the ball is firmly in the BFS camps court. Con won't and shouldn't deal with this, but any random BFS user with a bit of time could sit down and redo a set of benchmarks that _he_ feels is more relevant and use as a counterpoint. Maybe compiling vim on an Atom CPU as well as some measurements of dropped frames in mplayer while compiling? Latencies and stuttering may be hard to measure, but it is far from impossible. Something better than «it feels better when i shake my mouse» is needed.
Well, this settles it for me
disconnected from the desktop world. ingo's choice of hardware is not too
odd, but still unrealistic for most desktop users (or at least where i
live).
benchmarks. he thinks more like a desktop user.
enactment of scheduler flame-wars again.
Well, this settles it for me
Well, this settles it for me
Well, this settles it for me
Well, this settles it for me
- That the existing kernel developers have increased in their experience and skill and that standards for acceptance are therefore higher today
- That the stature of being a core kernel developer has risen and that ego may be involved
- That many parts of the kernel is near-optimal or at least very mature and that it is sensible to value stability in those areas
Well, this settles it for me
Well, this settles it for me
Well, this settles it for me
Because I can
As for netbooks, if interactivity (people keep posting about gaming FPS and high-def audio and high-res desktop experience) is such a concern, why are you using a netbook?
Because they are light and cute? You have not understood what "interactivity" means. People do not post about FPS or high-def audio per se, but about jitter, frame drops and audio skips. Those are really nasty when watching a movie or listening to music, and computers are said to be multitasking these days.
Because I can
You are right, there are no benchmarks that show that BFS is good at interactivity. However I contend that such "hand-waving" is to be expected from an anaesthetist and a crowd of enthusiasts (and is not a bad thing at all). The real pity is that on lkml, a list full of high-flying engineers, nobody has been able to construct those benchmarks or do those measurements either. The best we have is a scheduler hacker posting odd benchmarks on esoteric hardware. No offense for Ingo, he was very respectful and had interesting data, but it was all biased:
Interactive benchmarks
we tune the
Linux scheduler for desktop and small-server workloads mostly [...] what i
consider a sane range of systems to tune for - and should still fit
into BFS's design bracket as well according to your description:
it's a dual quad core system with hyperthreading
And then repeating the measures on a quad-core machine, the best he has offered so far. It seems that, despite having an expressed focus on the desktop, a netbook and a few days for testing on it are out of reach.
Interactive benchmarks
More to the point: even when one side proposed invalid benchmarks, the other side was not able to come up with anything better. (And no, "beat them at their own benchmarks" is not a valid excuse; we are talking about engineering, not about marketing.)
Interactive benchmarks
Well, this settles it for me
> disconnected from the desktop world. ingo's choice of hardware is not too
> odd, but still unrealistic for most desktop users (or at least where i
> live).
Well, this settles it for me
Well, this settles it for me
Well, this settles it for me
Well, this settles it for me
Well, this settles it for me
Well, this settles it for me
Well, this settles it for me
Well, this settles it for me
Maybe you're living on a different planet. The only time I've ever spent anything like that much was my first PC back in 1994 - a 66MHz 486.
Indeed. Although there can be good reasons for paying 1000 (or £1000) for a system, it's been a long time since anyone really had to. It reminds me of the "Killer PCs for £1500" idiocy the UK computing press used to run on the cover of their magazines every month back in the early-to-mid 1990s, and even at that time such dull retail summaries served the advertisers far more than they did the actual readership.
Well, this settles it for me
Well, this settles it for me
Well, this settles it for me
Well, this settles it for me
Ignor had every right to respond. [...] Have you read Ignor's email carefully or at all?
No, it's pronounced "Aye gnor". (Sorry, couldn't resist after the second mention.)
Well, this settles it for me
Well, this settles it for me