What is BPF and why is it taking over Linux Performance Analysis?
blog.memsql.com
blog.memsql.com
Histogram are better to see the repartitions of values, and can hint you on a n-modal behaviour. (a «mode» when everything goes well, and a degraded one for instance which can hint on a potential transition of behavior).
I guess the next step is to say this is even more important to know the evolution over time and announce that the equivalent of spectrogram (3D mapped on 2D plus colour) is a good idea to known towards which mode you are tending the more. [EDIT: which can also more significantly graphed as spectrum analysis, colour encoding the amplitude of measure for a given frequency, and frequency being 1/Period thus making sure that slow processes may appear between 0 and average]
A shortcut is to hire of of the many jobless guys with a master in science that actually have experience in labs.
Beware that for a reason that is beyond my reach, people with background in math, management, literature have problems with scientific concepts that has been discovered after 1800 unless it is packaged like magic.
When the data is good the result ist virtually identical. When there are outliers, the median just ignores them unless there lots of them. When the data is that bad, that the median doesn't work anymore you need to up your statistics quite a few notches.
Hence the reason I made my own backend for making very high precision measurement using a percentile filter (10%, 50%, 90% and average for the fun).
It was fun to watch linux «monotonic» clock not being monotonic.
I think some of the techniques might be applicable to system performance analysis, so I submit the following introductory publication, in case any are interested [0].
[0] http://opensiuc.lib.siu.edu/cgi/viewcontent.cgi?article=1077...
It's unfortunate that SystemTap never had much visbility. It also comes with a huge libraries of tapsets.
BPF/BCC solves most of this. You still have to have the sources so you can get the right targets for kprobes, but you don't have the compiler mismatch problem. You can now access the hash maps directly from user space so you can do things like build system monitoring tools that run in production and record really specific information easily. I used systemtap for years, but bcc/bpf is a whole new world.
If I was feeling less gracious, I might call into question whether you actually have no horse in this race, as apparently calling other people's motives and statements into question is apparently fair game for this thread.
While I certainly can be be wrong, I also wasn't assured it wasn't intentional by the way it was explained. I suggest we all mind phrasing and get along this way.
P.S. I don't find it gracious of you to imply that I might be a lying cheat.
I wasn't. I was using the idea that someone could imply that to point out your own behavior. That you took it as negatively as you did and assumed there was some deeper implication was the point (that is, that you could, not that it was intended). The only thing you didn't do is connect it to your own behavior in your prior comment.
If you can imagine a more tactful yet still effective alternative deterrent, I'm open to suggestions. I don't believe that just pointing out the fact of the use of the inappropriate tense would have been enough.
I think you interpreted the statement a specific way, and went about your response without considering that your interpretation may not have been their intent. If you had allowed for the possibility of misinterpretation, I imagine you might have been a bit less aggressive with the accusation initially.
> that that my tone was not as provokative.
My view of your tone was informed by your assertion of the intention of another commenter. I generally find it to be bad form to tell someone (correct them on) their intention, rather than your interpretation of their intention.
To clarify, stated as fact "It's not a typo" means you reject the original commenter's possible explanation, but since we're talking about their intent, that is in effect calling them a liar (since they are the canonical source of knowledge as to their intention).
Perhaps that wasn't your intention, and the downvotes you received were unwarranted. If so, you have my apologies, and my suggestion that you be careful about using absolutist terminology when referring to people's intentions when it contradicts their own assertions without supplying good evidence (in this case, the evidence you supplied did not negate other explanations). There's a high bar to adequately explaining someone is wrong about their professed reasoning, rightly so.
> If you can imagine a more tactful yet still effective alternative deterrent, I'm open to suggestions.
Originally: "I'm confused as to why you are using the past tense for SystemTap, the project is still very active."
In the follow up: "Are you sure typo is what you meant? Your last sentence seems to indicate it's in your past as well." (If you don't see that last sentence for what it is, an indication that SystemTap is in this person't past, and thus they refer to it in the past tense to relate their experience to some former version of it. This is useful to notify others that your information on the topic may not be completely current.)
EDIT: Admittedly I did assert there was a theme.
Your "seems" and "might" were modifiers on him "having a horse in this race." Unless your comments were meant to be taken entirely separately, the implication is "you are using the past tense because you have some vested interest in one of the projects." That's a fairly heavy accusation.
> The way I see it, it seems probable that OP was deceptive ... Your suggestion of how I should have handled it is exactly the option I considered inadequate.
See, I think this is one of those instances where your state of mind regarding this is coloring your interpretation of events. If you think that original comment using past tense was meant to imply the project was dead, I don't see that. To me that seems far less likely than the person used past tense because their experience was in the past, because I have done that myself, I see it on a regular basis, and I don't see people using it to imply a status of projects that doesn't match reality. Have you encountered this before?
> This is one of the longest threads I've been a party to on here, and no offense to you, but I'm not sure it was worth it.
Sure, I understand that. I'm responding because you're being civil in a discussion that's centered around a supposed mistake of yours, and I find understanding people's reasoning and state of mind when communicating to be somewhat interesting. Don't feel obligated to continue for my sake though.
You've already shared your opinion on the past tense and I've disagreed. I'll add to that the use of third person instead of the first. Hopefully this will be my last referral to the OC.
I'm simply claiming that it is probable that it was an attempt at manipulation and that my reaction had reason and purpose outweighing it's "harshness".
I don't want to continue this if you aren't getting anything out of it. My intent isn't to agitate.
> You can't just remove my modifiers and then claim "heavy accusations".
I'm not sure where I removed the modifiers? Even when tempered by modifiers, and accusation of being wrong required a different level of evidence than of wrongdoing, in my opinion. E.g. "I think you might be incorrect" compared to "I think you might be trying to deceive us". Even mentioning that you think someone is not acting in good faith should be reserved unless you are fairly certain (as outlined by the guidelines). Of course, as you've stated, you felt this situation was at that level. I think most people looking in did not, which is where the friction came from.
> Note also the irony of supposing someone's state of mind while advocating proof.
I don't think it's ironic to suppose a state of mind when the purpose is to give a benefit of a doubt. It's rude, and not conducive to discussion to assume negatively (and then act on it), I don't think the same can be said for asking for keeping an open mind and asking for clarification (without an accusation, or with one but making it very clear you are looking for an alternative explanation).
> You've already shared your opinion on the past tense and I've disagreed. I'll add to that the use of third person instead of the first. Hopefully this will be my last referral to the OC.
> I'm simply claiming that it is probable that it was an attempt at manipulation and that my reaction had reason and purpose outweighing it's "harshness".
Fair enough. I was just trying to understand how you weighted the probabilities of what you thought the commenter was trying to convey to make you think that was the probable intent, because we obviously interpreted it very differently. If you don't want to go into your reasoning, I'm not sure there's much else to say.
Obviously to explain was my exact intention, which is why I provided several arguments to your one.
Honestly, I find your first sentence hard to believe.
Because I was talking about the implication itself, not the whole sentence. The implication was clear.
> Obviously to explain was my exact intention, which is why I provided several arguments to your one.
You're convinced of the intent of the original commenter, I have doubts. It's natural that I don't need to provide as many arguments, I just need to justify enough reasonable doubt in your mind as to your assessment of the original comment to make you question whether your approach was appropriate (for whatever level that is for you).
The crux of this is your assessment of the original comment, but you're unwilling to revisit that. I've never experienced what you seem to think was going on here (IIUC, the use of past tense to imply an incorrect status of some project or person for the purpose increasing the estimation of the thing it is actively being compared to). That obviously colors whether I think that's a likely scenario for what we had. When pressed if you have experienced something like this before, or for any justification of why you think this rare (in my estimation) scenario is what we witnessed, you've decided you don't want to continue down that line of inquiry. That's your right, but I don't feel like there's much useful information to mine here with that avenue cut off, as I view it as the most relevant.
> Honestly, I find your first sentence hard to believe.
Yet you keep responding. I'll make it easy for you, since by that statement you've left me to conclude two likely situations. Either you really don't want to be part of this conversation but can't help yourself, or you think I'm not conversing in good conscience and am instead trying to troll you. Neither situation is one in which I feel comfortable continuing, so this will be my last reply in this thread. The best thing I can do to actually communicate my intent is to follow through on my statement that my intent is not to agitate.
Feel free to respond if you like, I'll be notified if you do and will read your response, so you have a chance to express any final thoughts you like on this issue or the conversation in general.
> It's unfortunate that SystemTap never had much visbility.
Right. DTrace was marketed. I don't think SystemTap was.
https://github.com/iovisor/bcc
Personal favorite: https://github.com/iovisor/bcc/blob/master/tools/sslsniff_ex...
This looks like a job for... FUNCTIONAL PROGRAMMING!
So if a scripting interface existed, would you use it? For what? Yes, it'd be nice to have, but I think a lot of people will get as far as using the provided bcc tools and be happy with that.