Messages in this thread | | | Date | Thu, 21 Jan 1999 20:16:01 +0100 (MET) | From | Max <> | Subject | Re: Tar (but not cp) is incredible slow on certain dirs; request for comments/solution ideas/clues. |
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On Thu, 21 Jan 1999, Dr. Michael Weller wrote:
>Anyway, effect under all those kernels/# of CPU's is as follows: I try to >backup / (whole linux is in one partition) to another disk, file on same >disk, or even /dev/null (it doesn't matter). It runs nicely. But when it >comes to /usr/src/linux-2.2.0pre7 where the 2.2.0pre7 sources are, it >slows down to a crawl. That means it backs up one of these really tiny *.c >and *.h files there per 1 or 2 seconds. Basically, it is impossible to >back this dir up in any reasonable time. > >I used tar -l as to exclude /proc and /mnt where the destination disk was >mounted. Still, even 'tar -cvf/dev/null /usr/src' showed the exact same >behaviour although it slowed down faster as it came faster to >/usr/src/linux-2.2.0pre7 . > >During the slow down, top claims system is well over 90% percent idle, >CPU time consumed by tar and general system time spent is virtually zero >(1 or 2 %). Tar is not locked in an uninterruptible sleep waiting for a >device ('D') nor is there any apparent high disk activity (it just gets >these tiny files every few seconds).
You could try # chown -R root: /usr/src/linux* and check if it makes any difference.
Something similar showed up on linux-kernel some time ago: it seems that tar finds those "strange" 1046/1046 values for uid/gid and asks around (i.e. to NYS) for them, sleeping while waiting for an answer.
>To make things even more weird, cp -rv /usr/src /mnt works like a greased >weasel. So, a simple filesystem/disk cache/dname cache/disk device or >driver issue can IMHO be excluded.
cp doesn't try to resolve uid/gid into names, tar does. So this *could* be a point for my explanation.
>Now, honestly, this is the very first time with linux I really have no >clue what's going on. Therefore any comments and ideas are appreciated.
I just sent my idea. Maybe I am wrong...
>Michael. >
Massimiliano Ghilardi
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