On Dienstag, 9. August 2011 Marc Lehmann wrote: > On Tue, Aug 09, 2011 at 12:10:48PM +0200, Michael Monnerie <michael.monnerie@xxxxxxxxxxxxxxxxxxx> wrote: > > First of all, please calm down. Getting personal is not bringing us > > anywhere. > > Well, it's not me who's getting personal, so...? A single rant from a dev shouldn't hurt one too much. He might have been sitting in front of some code during 72 hours, his eyes already being in 16:9 format staring at a weird bug... It's OK to strike back once, but then be cool again and work at the problem. > As has been reported on this list, this option is really harmful on > current xfs - in my case, it lead to xfs causing ENOSPC even when the > disk was 40% empty (~188gb). Was this the "NFS optimization" stuff? I don't like that either. > Well, if it were one fragment, you could read that in 4-5 seconds, at > 374 fragments, it's probably around 6-7 seconds. Thats not harmful, > but if you extrapolate this to a few gigabytes and a lot of files, > it becomes quite the overhead. True, if you have to read tons of log files all day. That's not my normal use case, so I didn't bother about that until now. > That allocsize option is no longer reasonable with newer kernels, as > the kernel will reserve 64m diskspace even for 1kb files > indefinitely. Just "as long as the inode is cached" or something, I remember that "echo 3 >drop_caches" cleans that up. Still ugly, I'd say. > If you find a way of recreating files without appending to them, let > me know. Seems we have a different meaning of "append". For me, append is when an existing file is re-opened, and data added just to the end of it. > > And maybe he could use it for optimizations. Is there any tool on > > Linux to record such I/O patterns? > > I presume strace would do, but thats where the "lot of work" comes > in. If there is a ready-to-use tool, that would of course make it > easy. It's a pity that such a generic tool doesn't existing. I can't believe that. Doesn't anybody have such a tool at hand? -- mit freundlichen Grüssen, Michael Monnerie, Ing. BSc it-management Internet Services: Protéger http://proteger.at [gesprochen: Prot-e-schee] Tel: +43 660 / 415 6531 // Haus zu verkaufen: http://zmi.at/langegg/
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