Comment 214 for bug 620074
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#214 |
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7020100
(Get the code!)
(In reply to comment #195)
> (In reply to comment #192)
> > It is therefore possible that your issue has more to do with the behaviour
> of
> > your SSD during writes than the kernel scheduler or anything else.
> >
>
> Well, if that is true, it would have to be a combination of the kernel and my
> system. Mainly because my system was SUPER fast before I tried upgrading my
> kernel past 2.6.17. As for my Mac, I don't recall having performance issues
> while running Mac OS X. Nothing like the article describes anyhow.
OK well in that case I absolutely agree it's obviously a software only problem in your case and probably this scheduler kernel issue. (I just wanted to point out for the record so everyone's aware, that there are some SSD hardware combinations that inherently have limitations that will may very well cause similar sluggishness regardless of the kernel/software itself.)
As an aside, high IO wait percentages are after all as far as I understand it not in and of themselves problematic, since high IO wait only means that a process is waiting for IO. This measure will therefore predictably be high when a process is doing heavy substantial IO with a comparatively slow device. Normally however one would expect such IO to not generally negatively affect other processes/general system reponsiveness, *except* if the other processes are also somehow IO hungry in order to proceed and you have some sort of IO resource contention going on, or as appears in this thread, there's actually a scheduling problem which causes processes that are runnable to not receive the CPU when they should, thus resulting in perceived sluggishness.