On 03.01.2008 02:16, Maxim Levitsky wrote: > On Wednesday, 2 January 2008 21:35:03 Matthias Schniedermeyer wrote: > > Hi > > > > > > Currently i'm deleting about 500.000 files on a XFS-filesystem which > > takes a few minutes, as i had a top open i saw that 'wa' is shown as > > 0.0% (Nothing else running currently) and everything except 'id' is near > > the bottom too. Kernel is 2.6.23.11. > > > > So, as 'rm -rf' is essentially a IO (or seek, to be more correct)-bound > > task, shouldn't that count as "Waiting for IO"? > > > > The man-page of top says: > > 'Amount of time the CPU has been waiting for I/O to complete.' > > > > But AFAICT wa only seams to be (ac)counted for writing and not for > > reading. I come to that conclusion because, when i fire 'sync' i can see > > some percent wa for a few seconds. > > The IOWAIT time is the IDLE time that was spent waiting > for I/O. (meaning that there were no tasks running, but some were waiting on > I/O) > > Thus if you have another task that is not I/O bound, it can run in that time, > and ideally, you shouldn't notice any I/O slowdown, but the iowait time will > decrease. > > It wasn't the case before CFS introduction. I did few tests that showed > almost 50% slowdown > when running another task in that iowait time. > It is not longer a problem with CFS.
I can understand that, but in my case nothing else was running, so i would expect about 46%-50% wa (Dual Core Processor). Bis denn -- Real Programmers consider "what you see is what you get" to be just as bad a concept in Text Editors as it is in women. No, the Real Programmer wants a "you asked for it, you got it" text editor -- complicated, cryptic, powerful, unforgiving, dangerous. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
