Ответ на сообщение «Re: Progress indicator for :TOhtml command», присланное в 19:39:15 05 июня 2010, Суббота, отправитель Benjamin Fritz:
Why do you need float math for progress bar? Integer division is enough unless you are going to show progress in %.1f or even more precious format. %3.d format that you are using is integer and you obviously can't show half of a character. Текст сообщения: > On Thu, Jun 3, 2010 at 10:03 PM, Benjamin Fritz <fritzophre...@gmail.com> wrote: > > This version is still not fast enough though. It is about 30% slower > > when the progress bar is enabled than when it is disabled. While I > > consider it a good tradeoff in most cases, we could certainly make it > > better. > > > > It would probably be faster to pre-calculate the line numbers needed > > to advance the progress bar rather than doing a bunch of > > floating-point math every cycle. > > I've attached a new version which pre-calculates the (integer) line > numbers needed to advance the progress bar. Now all the floating point > math is done once, up front. > > The difference is not really very perceptible. I timed the execution > on two files. First, I did the 5148-line autoload/phpcomplete.vim > script. Timings were as follows on my laptop: > > progress disabled: > average: 46 seconds > > floating-point progress: > average: 61 seconds > slowdown: 15 seconds longer than without progress bar > percentage: 33% longer than without progress bar > > precalculated progress: > average: 62 seconds > slowdown: 16 seconds longer than without progress bar > percentage: 35% longer than without progress bar > > Next I did a 33258-line C code file: > > progress disabled: > average: 691 seconds > > floating-point progress: > average: 716 seconds > slowdown: 25 seconds longer than without progress bar > percentage: 4% longer than without progress bar > > precalculated progress: > average: 711 seconds > slowdown: 20 seconds longer than without progress bar > percentage: 3% longer than without progress bar > > I also did a number of very small sections of files (my usual use case > for 2html) and did not notice any significant slowing; it only takes > 1-2 seconds longer for a 100 or 200 line selection. > > I take a few things from this. > > First of all, I don't think we'll get much performance improvement > with this method. I do not know whether it is setting the status line > and redrawing it, or whether it is the use of the object-oriented > style functions, but it would probably require a different approach to > get a significant speedup. I certainly like the look a lot better than > the echo method, even if we could get echon working. Is a 10-20 second > slow-down acceptable on large numbers of lines, if the normal > execution time is measured in minutes anyway? To me, it certainly is. > If something is going to be taking more than a few minutes, I want a > progress bar to tell me whether it's worth letting it continue. Since > the slow-down can be significant for midsize files, we will certainly > need to mention in the :help that disabling the progress bar will make > the conversion faster. Maybe we should only show the progress bar > after some amount of time has elapsed? We could suppress the > redrawstatus until 10 seconds have passed, or something like that. Any > thoughts? > > Secondly, the precalculated version is not really any faster than the > full floating-point calculation every cycle. I don't really have an > opinion of which method gives more readable code. Does anyone else > have any opinions on which version to keep? I think it would be > possible to do away with floating point calculations entirely using > the precalculated version; currently floating point is only used in > the calculate_ticks function. This might be desireable so that we can > remove the dependence on the +float feature, which is not marked with > a "smallest version" indicator in :help +feature-list. This apparently > means it is "system dependent". Does this mean float is pretty much > always included, unless it is explicitly removed? How common are Vims > without floating-point support? I already added use of the split() > function, which was added in version 7, so this won't work on really > old Vims...but do we want to support Vim 7.1 and earlier? >
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