https://bugzilla.novell.com/show_bug.cgi?id=387347 Harald Koenig changed: What |Removed |Added ---------------------------------------------------------------------------- Summary|pipe uses only 2 CPU on dual-core ("zcat | wc") |pipe uses only 1 CPU on dual-core ("zcat | wc") -- Configure bugmail: https://bugzilla.novell.com/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are on the CC list for the bug.

https://bugzilla.novell.com/show_bug.cgi?id=387347 User koenig@linux.de added comment https://bugzilla.novell.com/show_bug.cgi?id=387347#c2 Harald Koenig changed: What |Removed |Added ---------------------------------------------------------------------------- Status|RESOLVED |REOPENED Resolution|INVALID | --- Comment #2 from Harald Koenig 2008-05-07 01:41:20 MST --- (In reply to comment #1 from Greg Kroah-Hartman)

This is only a single process running, how could both cores be used for it?

please read again (or maybe try yourself?)! there are _two_ processes running for this test: gzip and wc, both using almost exactly the same amount of cpu bandwidth. actually, it's pretty hard using a pipe with only a single process, isn't it ;-) top shows _two_ processes, both only getting 50% cpu instead of 100% each, so I'm loosing a factor of 2 in real time (wall clock) performace. "procinfo -dn1" shows 50% idle -- that's the unused 2nd core!

This shows the scheduler is working quite well, and properly :)

NOPE. -- Configure bugmail: https://bugzilla.novell.com/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are on the CC list for the bug.

https://bugzilla.novell.com/show_bug.cgi?id=387347 User koenig@linux.de added comment https://bugzilla.novell.com/show_bug.cgi?id=387347#c4 Harald Koenig changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |aj@novell.com --- Comment #4 from Harald Koenig 2008-05-07 14:41:47 MST --- (In reply to comment #3 from Greg Kroah-Hartman)

On x86-64 box, you are right, it does seem to want to favor one processor, with almost one pegged at 100%, and the other around 10%.

But that doesn't mean the scheduler isn't working properly. As the workload seems about 50% for one cpu, putting both tasks on 1 cpu makes sense.

So again, I really don't see this being a problem.

from a user point of view (what's what I do the suse beta-tests for!) there _is_ a problem: for very simple and frequent operations (e.g. "pin") opensuse 11.0 will be 60% to 100% slower on dual-core compared to 10.3 ! here is the same timing running 10.3 with kernel 2.6.22.17-0.1-default: harald > time zcat /11.0/var/lib/pin/ARCHIVES.gz{,,,,,,,} | LC_ALL=C time wc > /dev/null 0:41.56 real, 27.32 user, 1.19 sys, 68% cpu 41.568 0m41.568s real, 63.952 user, 2.448 sys, 100.00 cpu (btw. that "100.00 cpu" [%] in the 10.3 output are bogus too -- bug bug;) unfortuneately that's not the only performace issue: there is this utf-8 issue for grep/wc/sed/... which gives a factor of 10+ of slowness (see bugs #308698 and #381873 -- thats an open issue since september 2007 found in 10.3-beta and never fixed so far :-(( I wonder why novell/suse does not handle these more reasonable way. I understand that kernel scheduler problems are very sensible issues, but at least this should be discussed and not closed as WONTFIX within hours :-( not handling the utf-8 problems for a full distribution cycle is just insane IMHO. so I wonder where is novell/suse going with their products (both opensuse and SLES) ???? I'm ver disapointed to see this development, being a happy suse user and active beta-tester and developer for far more than 10 years...

If you disagree, please create a bug at bugzilla.kernel.org as this is an upstream issue, we do not change the scheduler at all in our opensuse kernels.

IMHO _you_ (suse) should be interested to get this thing work better -- if possible before releasing 11.0-GM or at least with a kernel update real soon after 11.0-release.... marking this WONTFIX so fast won't help neither your users nor suse. -- Configure bugmail: https://bugzilla.novell.com/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are on the CC list for the bug.